Tidy nullptr usage

Move away from using 0 as pointer literal.

Done using clang-tidy. This is not complete as
run-clang-tidy can't handle all of qtbase in one go.

Change-Id: I1076a21f32aac0dab078af6f175f7508145eece0
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

135 files changed, 1752 insertions, 1752 deletions

diff --git a/src/widgets/accessible/complexwidgets.cpp b/src/widgets/accessible/complexwidgets.cpp
index 63c6fbb9bb..4d9a629ab6 100644
--- a/src/widgets/accessible/complexwidgets.cpp
+++ b/src/widgets/accessible/complexwidgets.cpp
@@ -97,10 +97,10 @@ public:
         if (t == QAccessible::ActionInterface) {
             return static_cast<QAccessibleActionInterface*>(this);
         }
-        return 0;
+        return nullptr;
     }
 
-    QObject *object() const override { return 0; }
+    QObject *object() const override { return nullptr; }
     QAccessible::Role role() const override { return QAccessible::PageTab; }
     QAccessible::State state() const override {
         if (!isValid()) {
@@ -129,7 +129,7 @@ public:
         return false;
     }
 
-    QAccessibleInterface *childAt(int, int) const override { return 0; }
+    QAccessibleInterface *childAt(int, int) const override { return nullptr; }
     int childCount() const override { return 0; }
     int indexOfChild(const QAccessibleInterface *) const override  { return -1; }
 
@@ -168,7 +168,7 @@ public:
     QAccessibleInterface *parent() const override {
         return QAccessible::queryAccessibleInterface(m_parent.data());
     }
-    QAccessibleInterface *child(int) const override { return 0; }
+    QAccessibleInterface *child(int) const override { return nullptr; }
 
     // action interface
     QStringList actionNames() const override
@@ -237,7 +237,7 @@ QAccessibleInterface* QAccessibleTabBar::child(int index) const
             return QAccessible::queryAccessibleInterface(tabBar()->d_func()->rightB);
         }
     }
-    return 0;
+    return nullptr;
 }
 
 int QAccessibleTabBar::indexOfChild(const QAccessibleInterface *child) const
@@ -314,7 +314,7 @@ QAccessibleInterface *QAccessibleComboBox::child(int index) const
     } else if (index == 1 && comboBox()->isEditable()) {
         return QAccessible::queryAccessibleInterface(comboBox()->lineEdit());
     }
-    return 0;
+    return nullptr;
 }
 
 int QAccessibleComboBox::childCount() const
@@ -327,7 +327,7 @@ QAccessibleInterface *QAccessibleComboBox::childAt(int x, int y) const
 {
     if (comboBox()->isEditable() && comboBox()->lineEdit()->rect().contains(x, y))
         return child(1);
-    return 0;
+    return nullptr;
 }
 
 int QAccessibleComboBox::indexOfChild(const QAccessibleInterface *child) const
@@ -432,7 +432,7 @@ bool QAccessibleAbstractScrollArea::isValid() const
 QAccessibleInterface *QAccessibleAbstractScrollArea::childAt(int x, int y) const
 {
     if (!abstractScrollArea()->isVisible())
-        return 0;
+        return nullptr;
 
     for (int i = 0; i < childCount(); ++i) {
         QPoint wpos = accessibleChildren().at(i)->mapToGlobal(QPoint(0, 0));
@@ -440,7 +440,7 @@ QAccessibleInterface *QAccessibleAbstractScrollArea::childAt(int x, int y) const
         if (rect.contains(x, y))
             return child(i);
     }
-    return 0;
+    return nullptr;
 }
 
 QAbstractScrollArea *QAccessibleAbstractScrollArea::abstractScrollArea() const
diff --git a/src/widgets/accessible/itemviews.cpp b/src/widgets/accessible/itemviews.cpp
index 3bfe215c05..5a7fdf9a03 100644
--- a/src/widgets/accessible/itemviews.cpp
+++ b/src/widgets/accessible/itemviews.cpp
@@ -121,7 +121,7 @@ QAccessibleTable::~QAccessibleTable()
 
 QHeaderView *QAccessibleTable::horizontalHeader() const
 {
-    QHeaderView *header = 0;
+    QHeaderView *header = nullptr;
     if (false) {
 #if QT_CONFIG(tableview)
     } else if (const QTableView *tv = qobject_cast<const QTableView*>(view())) {
@@ -137,7 +137,7 @@ QHeaderView *QAccessibleTable::horizontalHeader() const
 
 QHeaderView *QAccessibleTable::verticalHeader() const
 {
-    QHeaderView *header = 0;
+    QHeaderView *header = nullptr;
     if (false) {
 #if QT_CONFIG(tableview)
     } else if (const QTableView *tv = qobject_cast<const QTableView*>(view())) {
@@ -150,19 +150,19 @@ QHeaderView *QAccessibleTable::verticalHeader() const
 QAccessibleInterface *QAccessibleTable::cellAt(int row, int column) const
 {
     if (!view()->model())
-        return 0;
+        return nullptr;
     Q_ASSERT(role() != QAccessible::Tree);
     QModelIndex index = view()->model()->index(row, column, view()->rootIndex());
     if (Q_UNLIKELY(!index.isValid())) {
         qWarning() << "QAccessibleTable::cellAt: invalid index: " << index << " for " << view();
-        return 0;
+        return nullptr;
     }
     return child(logicalIndex(index));
 }
 
 QAccessibleInterface *QAccessibleTable::caption() const
 {
-    return 0;
+    return nullptr;
 }
 
 QString QAccessibleTable::columnDescription(int column) const
@@ -254,7 +254,7 @@ QList<int> QAccessibleTable::selectedRows() const
 
 QAccessibleInterface *QAccessibleTable::summary() const
 {
-    return 0;
+    return nullptr;
 }
 
 bool QAccessibleTable::isColumnSelected(int column) const
@@ -422,7 +422,7 @@ QAccessibleInterface *QAccessibleTable::childAt(int x, int y) const
     if (index.isValid()) {
         return child(logicalIndex(index));
     }
-    return 0;
+    return nullptr;
 }
 
 int QAccessibleTable::childCount() const
@@ -485,13 +485,13 @@ QAccessibleInterface *QAccessibleTable::parent() const
         }
         return QAccessible::queryAccessibleInterface(view()->parent());
     }
-    return 0;
+    return nullptr;
 }
 
 QAccessibleInterface *QAccessibleTable::child(int logicalIndex) const
 {
     if (!view()->model())
-        return 0;
+        return nullptr;
 
     auto id = childToId.constFind(logicalIndex);
     if (id != childToId.constEnd())
@@ -505,7 +505,7 @@ QAccessibleInterface *QAccessibleTable::child(int logicalIndex) const
     int row = logicalIndex / columns;
     int column = logicalIndex % columns;
 
-    QAccessibleInterface *iface = 0;
+    QAccessibleInterface *iface = nullptr;
 
     if (vHeader) {
         if (column == 0) {
@@ -528,7 +528,7 @@ QAccessibleInterface *QAccessibleTable::child(int logicalIndex) const
         QModelIndex index = view()->model()->index(row, column, view()->rootIndex());
         if (Q_UNLIKELY(!index.isValid())) {
             qWarning("QAccessibleTable::child: Invalid index at: %d %d", row, column);
-            return 0;
+            return nullptr;
         }
         iface = new QAccessibleTableCell(view(), index, cellRole());
     }
@@ -542,7 +542,7 @@ void *QAccessibleTable::interface_cast(QAccessible::InterfaceType t)
 {
     if (t == QAccessible::TableInterface)
        return static_cast<QAccessibleTableInterface*>(this);
-   return 0;
+   return nullptr;
 }
 
 void QAccessibleTable::modelChange(QAccessibleTableModelChangeEvent *event)
@@ -676,13 +676,13 @@ QModelIndex QAccessibleTree::indexFromLogical(int row, int column) const
 QAccessibleInterface *QAccessibleTree::childAt(int x, int y) const
 {
     if (!view()->model())
-        return 0;
+        return nullptr;
     QPoint viewportOffset = view()->viewport()->mapTo(view(), QPoint(0,0));
     QPoint indexPosition = view()->mapFromGlobal(QPoint(x, y) - viewportOffset);
 
     QModelIndex index = view()->indexAt(indexPosition);
     if (!index.isValid())
-        return 0;
+        return nullptr;
 
     const QTreeView *treeView = qobject_cast<const QTreeView*>(view());
     int row = treeView->d_func()->viewIndex(index) + (horizontalHeader() ? 1 : 0);
@@ -706,9 +706,9 @@ int QAccessibleTree::childCount() const
 QAccessibleInterface *QAccessibleTree::child(int logicalIndex) const
 {
     if (logicalIndex < 0 || !view()->model() || !view()->model()->columnCount())
-        return 0;
+        return nullptr;
 
-    QAccessibleInterface *iface = 0;
+    QAccessibleInterface *iface = nullptr;
     int index = logicalIndex;
 
     if (horizontalHeader()) {
@@ -724,7 +724,7 @@ QAccessibleInterface *QAccessibleTree::child(int logicalIndex) const
         int column = index % view()->model()->columnCount();
         QModelIndex modelIndex = indexFromLogical(row, column);
         if (!modelIndex.isValid())
-            return 0;
+            return nullptr;
         iface = new QAccessibleTableCell(view(), modelIndex, cellRole());
     }
     QAccessible::registerAccessibleInterface(iface);
@@ -772,7 +772,7 @@ QAccessibleInterface *QAccessibleTree::cellAt(int row, int column) const
     QModelIndex index = indexFromLogical(row, column);
     if (Q_UNLIKELY(!index.isValid())) {
         qWarning("Requested invalid tree cell: %d %d", row, column);
-        return 0;
+        return nullptr;
     }
     const QTreeView *treeView = qobject_cast<const QTreeView*>(view());
     Q_ASSERT(treeView);
@@ -841,7 +841,7 @@ void *QAccessibleTableCell::interface_cast(QAccessible::InterfaceType t)
         return static_cast<QAccessibleTableCellInterface*>(this);
     if (t == QAccessible::ActionInterface)
         return static_cast<QAccessibleActionInterface*>(this);
-    return 0;
+    return nullptr;
 }
 
 int QAccessibleTableCell::columnExtent() const { return 1; }
@@ -869,7 +869,7 @@ QList<QAccessibleInterface*> QAccessibleTableCell::columnHeaderCells() const
 
 QHeaderView *QAccessibleTableCell::horizontalHeader() const
 {
-    QHeaderView *header = 0;
+    QHeaderView *header = nullptr;
 
     if (false) {
 #if QT_CONFIG(tableview)
@@ -887,7 +887,7 @@ QHeaderView *QAccessibleTableCell::horizontalHeader() const
 
 QHeaderView *QAccessibleTableCell::verticalHeader() const
 {
-    QHeaderView *header = 0;
+    QHeaderView *header = nullptr;
 #if QT_CONFIG(tableview)
     if (const QTableView *tv = qobject_cast<const QTableView*>(view))
         header = tv->verticalHeader();
@@ -1115,7 +1115,7 @@ QAccessibleInterface *QAccessibleTableCell::parent() const
 
 QAccessibleInterface *QAccessibleTableCell::child(int) const
 {
-    return 0;
+    return nullptr;
 }
 
 QAccessibleTableHeaderCell::QAccessibleTableHeaderCell(QAbstractItemView *view_, int index_, Qt::Orientation orientation_)
@@ -1143,7 +1143,7 @@ QAccessible::State QAccessibleTableHeaderCell::state() const
 
 QRect QAccessibleTableHeaderCell::rect() const
 {
-    QHeaderView *header = 0;
+    QHeaderView *header = nullptr;
     if (false) {
 #if QT_CONFIG(tableview)
     } else if (const QTableView *tv = qobject_cast<const QTableView*>(view)) {
@@ -1206,12 +1206,12 @@ QAccessibleInterface *QAccessibleTableHeaderCell::parent() const
 
 QAccessibleInterface *QAccessibleTableHeaderCell::child(int) const
 {
-    return 0;
+    return nullptr;
 }
 
 QHeaderView *QAccessibleTableHeaderCell::headerView() const
 {
-    QHeaderView *header = 0;
+    QHeaderView *header = nullptr;
     if (false) {
 #if QT_CONFIG(tableview)
     } else if (const QTableView *tv = qobject_cast<const QTableView*>(view)) {
diff --git a/src/widgets/accessible/qaccessiblemenu.cpp b/src/widgets/accessible/qaccessiblemenu.cpp
index 7f87288520..51ba0adaa6 100644
--- a/src/widgets/accessible/qaccessiblemenu.cpp
+++ b/src/widgets/accessible/qaccessiblemenu.cpp
@@ -88,8 +88,8 @@ QAccessibleInterface *QAccessibleMenu::childAt(int x, int y) const
 {
     QAction *act = menu()->actionAt(menu()->mapFromGlobal(QPoint(x,y)));
     if(act && act->isSeparator())
-        act = 0;
-    return act ? getOrCreateMenu(menu(), act) : 0;
+        act = nullptr;
+    return act ? getOrCreateMenu(menu(), act) : nullptr;
 }
 
 QString QAccessibleMenu::text(QAccessible::Text t) const
@@ -112,7 +112,7 @@ QAccessibleInterface *QAccessibleMenu::child(int index) const
 {
     if (index < childCount())
         return getOrCreateMenu(menu(), menu()->actions().at(index));
-    return 0;
+    return nullptr;
 }
 
 QAccessibleInterface *QAccessibleMenu::parent() const
@@ -165,7 +165,7 @@ QAccessibleInterface *QAccessibleMenuBar::child(int index) const
     if (index < childCount()) {
         return getOrCreateMenu(menuBar(), menuBar()->actions().at(index));
     }
-    return 0;
+    return nullptr;
 }
 
 int QAccessibleMenuBar::indexOfChild(const QAccessibleInterface *child) const
@@ -195,7 +195,7 @@ QAccessibleInterface *QAccessibleMenuItem::childAt(int x, int y ) const
             return childInterface;
         }
     }
-    return 0;
+    return nullptr;
 }
 
 int QAccessibleMenuItem::childCount() const
@@ -224,14 +224,14 @@ QAccessibleInterface *QAccessibleMenuItem::child(int index) const
 {
     if (index == 0 && action()->menu())
         return QAccessible::queryAccessibleInterface(action()->menu());
-    return 0;
+    return nullptr;
 }
 
 void *QAccessibleMenuItem::interface_cast(QAccessible::InterfaceType t)
 {
     if (t == QAccessible::ActionInterface)
         return static_cast<QAccessibleActionInterface*>(this);
-    return 0;
+    return nullptr;
 }
 
 QObject *QAccessibleMenuItem::object() const
diff --git a/src/widgets/accessible/qaccessiblewidget.cpp b/src/widgets/accessible/qaccessiblewidget.cpp
index 27e6b09dc7..c782e00f4f 100644
--- a/src/widgets/accessible/qaccessiblewidget.cpp
+++ b/src/widgets/accessible/qaccessiblewidget.cpp
@@ -363,7 +363,7 @@ QAccessibleInterface *QAccessibleWidget::child(int index) const
     QWidgetList childList = childWidgets(widget());
     if (index >= 0 && index < childList.size())
         return QAccessible::queryAccessibleInterface(childList.at(index));
-    return 0;
+    return nullptr;
 }
 
 /*! \reimp */
@@ -374,11 +374,11 @@ QAccessibleInterface *QAccessibleWidget::focusChild() const
 
     QWidget *fw = widget()->focusWidget();
     if (!fw)
-        return 0;
+        return nullptr;
 
     if (isAncestor(widget(), fw) || fw == widget())
         return QAccessible::queryAccessibleInterface(fw);
-    return 0;
+    return nullptr;
 }
 
 /*! \reimp */
@@ -522,7 +522,7 @@ void *QAccessibleWidget::interface_cast(QAccessible::InterfaceType t)
 {
     if (t == QAccessible::ActionInterface)
        return static_cast<QAccessibleActionInterface*>(this);
-    return 0;
+    return nullptr;
 }
 
 QT_END_NAMESPACE
diff --git a/src/widgets/accessible/qaccessiblewidgetfactory.cpp b/src/widgets/accessible/qaccessiblewidgetfactory.cpp
index 0bac45de27..d59da86076 100644
--- a/src/widgets/accessible/qaccessiblewidgetfactory.cpp
+++ b/src/widgets/accessible/qaccessiblewidgetfactory.cpp
@@ -62,7 +62,7 @@ QT_BEGIN_NAMESPACE
 
 QAccessibleInterface *qAccessibleFactory(const QString &classname, QObject *object)
 {
-    QAccessibleInterface *iface = 0;
+    QAccessibleInterface *iface = nullptr;
     if (!object || !object->isWidgetType())
         return iface;
 
@@ -79,7 +79,7 @@ QAccessibleInterface *qAccessibleFactory(const QString &classname, QObject *obje
 #if QT_CONFIG(lineedit)
     } else if (classname == QLatin1String("QLineEdit")) {
         if (widget->objectName() == QLatin1String("qt_spinbox_lineedit"))
-            iface = 0;
+            iface = nullptr;
         else
             iface = new QAccessibleLineEdit(widget);
 #endif
@@ -223,7 +223,7 @@ QAccessibleInterface *qAccessibleFactory(const QString &classname, QObject *obje
 #endif
 
     } else if (classname == QLatin1String("QDesktopScreenWidget")) {
-        iface = 0;
+        iface = nullptr;
     } else if (classname == QLatin1String("QWidget")) {
         iface = new QAccessibleWidget(widget);
     } else if (classname == QLatin1String("QWindowContainer")) {
diff --git a/src/widgets/accessible/qaccessiblewidgets.cpp b/src/widgets/accessible/qaccessiblewidgets.cpp
index 52c953ed3a..574be1f5ea 100644
--- a/src/widgets/accessible/qaccessiblewidgets.cpp
+++ b/src/widgets/accessible/qaccessiblewidgets.cpp
@@ -332,14 +332,14 @@ QAccessibleStackedWidget::QAccessibleStackedWidget(QWidget *widget)
 QAccessibleInterface *QAccessibleStackedWidget::childAt(int x, int y) const
 {
     if (!stackedWidget()->isVisible())
-        return 0;
+        return nullptr;
     QWidget *currentWidget = stackedWidget()->currentWidget();
     if (!currentWidget)
-        return 0;
+        return nullptr;
     QPoint position = currentWidget->mapFromGlobal(QPoint(x, y));
     if (currentWidget->rect().contains(position))
         return child(stackedWidget()->currentIndex());
-    return 0;
+    return nullptr;
 }
 
 int QAccessibleStackedWidget::childCount() const
@@ -359,7 +359,7 @@ int QAccessibleStackedWidget::indexOfChild(const QAccessibleInterface *child) co
 QAccessibleInterface *QAccessibleStackedWidget::child(int index) const
 {
     if (index < 0 || index >= stackedWidget()->count())
-        return 0;
+        return nullptr;
     return QAccessible::queryAccessibleInterface(stackedWidget()->widget(index));
 }
 
@@ -401,7 +401,7 @@ QAccessibleInterface *QAccessibleMdiArea::child(int index) const
     QList<QMdiSubWindow *> subWindows = mdiArea()->subWindowList();
     QWidget *targetObject = subWindows.value(index);
     if (!targetObject)
-       return 0;
+       return nullptr;
     return QAccessible::queryAccessibleInterface(targetObject);
 }
 
@@ -478,7 +478,7 @@ QAccessibleInterface *QAccessibleMdiSubWindow::child(int index) const
 {
     QMdiSubWindow *source = mdiSubWindow();
     if (index != 0 || !source->widget())
-        return 0;
+        return nullptr;
 
     return QAccessible::queryAccessibleInterface(source->widget());
 }
@@ -554,7 +554,7 @@ int QAccessibleCalendarWidget::indexOfChild(const QAccessibleInterface *child) c
 QAccessibleInterface *QAccessibleCalendarWidget::child(int index) const
 {
     if (index < 0 || index >= childCount())
-        return 0;
+        return nullptr;
 
     if (childCount() > 1 && index == 0)
         return QAccessible::queryAccessibleInterface(navigationBar());
@@ -573,7 +573,7 @@ QAbstractItemView *QAccessibleCalendarWidget::calendarView() const
         if (child->objectName() == QLatin1String("qt_calendar_calendarview"))
             return static_cast<QAbstractItemView *>(child);
     }
-    return 0;
+    return nullptr;
 }
 
 QWidget *QAccessibleCalendarWidget::navigationBar() const
@@ -582,7 +582,7 @@ QWidget *QAccessibleCalendarWidget::navigationBar() const
         if (child->objectName() == QLatin1String("qt_calendar_navigationbar"))
             return static_cast<QWidget *>(child);
     }
-    return 0;
+    return nullptr;
 }
 #endif // QT_CONFIG(calendarwidget)
 
@@ -624,7 +624,7 @@ QAccessibleInterface *QAccessibleDockWidget::child(int index) const
         if (item)
             return QAccessible::queryAccessibleInterface(item->widget());
     }
-    return 0;
+    return nullptr;
 }
 
 int QAccessibleDockWidget::indexOfChild(const QAccessibleInterface *child) const
@@ -1109,7 +1109,7 @@ QAccessibleInterface *QAccessibleMainWindow::child(int index) const
     if (index >= 0 && index < kids.count()) {
         return QAccessible::queryAccessibleInterface(kids.at(index));
     }
-    return 0;
+    return nullptr;
 }
 
 int QAccessibleMainWindow::childCount() const
@@ -1128,10 +1128,10 @@ QAccessibleInterface *QAccessibleMainWindow::childAt(int x, int y) const
 {
     QWidget *w = widget();
     if (!w->isVisible())
-        return 0;
+        return nullptr;
     QPoint gp = w->mapToGlobal(QPoint(0, 0));
     if (!QRect(gp.x(), gp.y(), w->width(), w->height()).contains(x, y))
-        return 0;
+        return nullptr;
 
     const QWidgetList kids = childWidgets(mainWindow());
     QPoint rp = mainWindow()->mapFromGlobal(QPoint(x, y));
@@ -1140,7 +1140,7 @@ QAccessibleInterface *QAccessibleMainWindow::childAt(int x, int y) const
             return QAccessible::queryAccessibleInterface(child);
         }
     }
-    return 0;
+    return nullptr;
 }
 
 QMainWindow *QAccessibleMainWindow::mainWindow() const
diff --git a/src/widgets/accessible/simplewidgets.cpp b/src/widgets/accessible/simplewidgets.cpp
index ca74ee4b12..9dbbe9c608 100644
--- a/src/widgets/accessible/simplewidgets.cpp
+++ b/src/widgets/accessible/simplewidgets.cpp
@@ -364,7 +364,7 @@ QAccessibleInterface *QAccessibleToolButton::child(int index) const
 #else
     Q_UNUSED(index)
 #endif
-    return 0;
+    return nullptr;
 }
 
 /*
@@ -976,7 +976,7 @@ QAccessibleInterface *QAccessibleWindowContainer::child(int i) const
 {
     if (i == 0)
         return QAccessible::queryAccessibleInterface(container()->containedWindow());
-    return 0;
+    return nullptr;
 }
 
 QWindowContainer *QAccessibleWindowContainer::container() const
diff --git a/src/widgets/dialogs/qcolordialog.cpp b/src/widgets/dialogs/qcolordialog.cpp
index d00a600424..689002b589 100644
--- a/src/widgets/dialogs/qcolordialog.cpp
+++ b/src/widgets/dialogs/qcolordialog.cpp
@@ -192,7 +192,7 @@ class QWellArray : public QWidget
     Q_PROPERTY(int selectedRow READ selectedRow)
 
 public:
-    QWellArray(int rows, int cols, QWidget* parent=0);
+    QWellArray(int rows, int cols, QWidget* parent=nullptr);
     ~QWellArray() {}
     QString cellContent(int row, int col) const;
 
@@ -744,7 +744,7 @@ class QColorLuminancePicker : public QWidget
 {
     Q_OBJECT
 public:
-    QColorLuminancePicker(QWidget* parent=0);
+    QColorLuminancePicker(QWidget* parent=nullptr);
     ~QColorLuminancePicker();
 
 public slots:
@@ -789,7 +789,7 @@ QColorLuminancePicker::QColorLuminancePicker(QWidget* parent)
     :QWidget(parent)
 {
     hue = 100; val = 100; sat = 100;
-    pix = 0;
+    pix = nullptr;
     //    setAttribute(WA_NoErase, true);
 }
 
@@ -812,7 +812,7 @@ void QColorLuminancePicker::setVal(int v)
     if (val == v)
         return;
     val = qMax(0, qMin(v,255));
-    delete pix; pix=0;
+    delete pix; pix=nullptr;
     repaint();
     emit newHsv(hue, sat, val);
 }
@@ -861,7 +861,7 @@ void QColorLuminancePicker::setCol(int h, int s , int v)
     val = v;
     hue = h;
     sat = s;
-    delete pix; pix=0;
+    delete pix; pix=nullptr;
     repaint();
 }
 
@@ -1678,8 +1678,8 @@ void QColorDialogPrivate::init(const QColor &initial)
     q->setWindowTitle(QColorDialog::tr("Select Color"));
 
     // default: use the native dialog if possible.  Can be overridden in setOptions()
-    nativeDialogInUse = (platformColorDialogHelper() != 0);
-    colorPickingEventFilter = 0;
+    nativeDialogInUse = (platformColorDialogHelper() != nullptr);
+    colorPickingEventFilter = nullptr;
     nextCust = 0;
 
     if (!nativeDialogInUse)
@@ -1703,7 +1703,7 @@ void QColorDialogPrivate::initWidgets()
     QHBoxLayout *topLay = new QHBoxLayout();
     mainLay->addLayout(topLay);
 
-    leftLay = 0;
+    leftLay = nullptr;
 
 #if defined(QT_SMALL_COLORDIALOG)
     smallDisplay = true;
@@ -1773,8 +1773,8 @@ void QColorDialogPrivate::initWidgets()
         pWidth = 150;
         pHeight = 100;
 #endif
-        custom = 0;
-        standard = 0;
+        custom = nullptr;
+        standard = nullptr;
     }
 
     QVBoxLayout *rightLay = new QVBoxLayout;
@@ -2302,7 +2302,7 @@ void QColorDialog::done(int result)
     if (d->receiverToDisconnectOnClose) {
         disconnect(this, SIGNAL(colorSelected(QColor)),
                    d->receiverToDisconnectOnClose, d->memberToDisconnectOnClose);
-        d->receiverToDisconnectOnClose = 0;
+        d->receiverToDisconnectOnClose = nullptr;
     }
     d->memberToDisconnectOnClose.clear();
 }
diff --git a/src/widgets/dialogs/qdialog.cpp b/src/widgets/dialogs/qdialog.cpp
index 3cdd9a5f04..362200a4fd 100644
--- a/src/widgets/dialogs/qdialog.cpp
+++ b/src/widgets/dialogs/qdialog.cpp
@@ -187,7 +187,7 @@ QWindow *QDialogPrivate::transientParentWindow() const
         return parent->windowHandle();
     else if (q->windowHandle())
         return q->windowHandle()->transientParent();
-    return 0;
+    return nullptr;
 }
 
 bool QDialogPrivate::setNativeDialogVisible(bool visible)
@@ -214,7 +214,7 @@ QVariant QDialogPrivate::styleHint(QPlatformDialogHelper::StyleHint hint) const
 void QDialogPrivate::deletePlatformHelper()
 {
     delete m_platformHelper;
-    m_platformHelper = 0;
+    m_platformHelper = nullptr;
     m_platformHelperCreated = false;
     nativeDialogInUse = false;
 }
@@ -460,7 +460,7 @@ void QDialogPrivate::setDefault(QPushButton *pushButton)
 */
 void QDialogPrivate::setMainDefault(QPushButton *pushButton)
 {
-    mainDef = 0;
+    mainDef = nullptr;
     setDefault(pushButton);
 }
 
@@ -602,7 +602,7 @@ int QDialog::exec()
     }
     if (guard.isNull())
         return QDialog::Rejected;
-    d->eventLoop = 0;
+    d->eventLoop = nullptr;
 
     setAttribute(Qt::WA_ShowModal, wasShowModal);
 
@@ -679,12 +679,12 @@ void QDialog::contextMenuEvent(QContextMenuEvent *e)
 #else
     QWidget *w = childAt(e->pos());
     if (!w) {
-        w = rect().contains(e->pos()) ? this : 0;
+        w = rect().contains(e->pos()) ? this : nullptr;
         if (!w)
             return;
     }
     while (w && w->whatsThis().size() == 0 && !w->testAttribute(Qt::WA_CustomWhatsThis))
-        w = w->isWindow() ? 0 : w->parentWidget();
+        w = w->isWindow() ? nullptr : w->parentWidget();
     if (w) {
         QPointer<QMenu> p = new QMenu(this);
         QAction *wt = p.data()->addAction(tr("What's This?"));
@@ -1191,7 +1191,7 @@ void QDialog::setSizeGripEnabled(bool enabled)
             d->resizer->show();
         } else {
             delete d->resizer;
-            d->resizer = 0;
+            d->resizer = nullptr;
         }
     }
 #endif // QT_CONFIG(sizegrip)
diff --git a/src/widgets/dialogs/qerrormessage.cpp b/src/widgets/dialogs/qerrormessage.cpp
index f0ec2c0102..790d09414b 100644
--- a/src/widgets/dialogs/qerrormessage.cpp
+++ b/src/widgets/dialogs/qerrormessage.cpp
@@ -149,13 +149,13 @@ QSize QErrorMessageTextView::sizeHint() const
     \sa QMessageBox, QStatusBar::showMessage(), {Standard Dialogs Example}
 */
 
-static QErrorMessage * qtMessageHandler = 0;
+static QErrorMessage * qtMessageHandler = nullptr;
 
 static void deleteStaticcQErrorMessage() // post-routine
 {
     if (qtMessageHandler) {
         delete qtMessageHandler;
-        qtMessageHandler = 0;
+        qtMessageHandler = nullptr;
     }
 }
 
@@ -252,8 +252,8 @@ QErrorMessage::QErrorMessage(QWidget * parent)
 QErrorMessage::~QErrorMessage()
 {
     if (this == qtMessageHandler) {
-        qtMessageHandler = 0;
-        QtMessageHandler tmp = qInstallMessageHandler(0);
+        qtMessageHandler = nullptr;
+        QtMessageHandler tmp = qInstallMessageHandler(nullptr);
         // in case someone else has later stuck in another...
         if (tmp != jump)
             qInstallMessageHandler(tmp);
@@ -293,7 +293,7 @@ void QErrorMessage::done(int a)
 QErrorMessage * QErrorMessage::qtHandler()
 {
     if (!qtMessageHandler) {
-        qtMessageHandler = new QErrorMessage(0);
+        qtMessageHandler = new QErrorMessage(nullptr);
         qAddPostRoutine(deleteStaticcQErrorMessage); // clean up
         qtMessageHandler->setWindowTitle(QCoreApplication::applicationName());
         qInstallMessageHandler(jump);
diff --git a/src/widgets/dialogs/qfiledialog.cpp b/src/widgets/dialogs/qfiledialog.cpp
index fbcc02accd..f0bd08a778 100644
--- a/src/widgets/dialogs/qfiledialog.cpp
+++ b/src/widgets/dialogs/qfiledialog.cpp
@@ -531,15 +531,15 @@ void QFileDialog::changeEvent(QEvent *e)
 QFileDialogPrivate::QFileDialogPrivate()
     :
 #if QT_CONFIG(proxymodel)
-        proxyModel(0),
+        proxyModel(nullptr),
 #endif
-        model(0),
+        model(nullptr),
         currentHistoryLocation(-1),
-        renameAction(0),
-        deleteAction(0),
-        showHiddenAction(0),
+        renameAction(nullptr),
+        deleteAction(nullptr),
+        showHiddenAction(nullptr),
         useDefaultCaption(true),
-        qFileDialogUi(0),
+        qFileDialogUi(nullptr),
         options(QFileDialogOptions::create())
 {
 }
@@ -882,14 +882,14 @@ void QFileDialog::setVisible(bool visible)
 #if QT_CONFIG(fscompleter)
             // So the completer doesn't try to complete and therefore show a popup
             if (!d->nativeDialogInUse)
-                d->completer->setModel(0);
+                d->completer->setModel(nullptr);
 #endif
         } else {
             d->createWidgets();
             setAttribute(Qt::WA_DontShowOnScreen, false);
 #if QT_CONFIG(fscompleter)
             if (!d->nativeDialogInUse) {
-                if (d->proxyModel != 0)
+                if (d->proxyModel != nullptr)
                     d->completer->setModel(d->proxyModel);
                 else
                     d->completer->setModel(d->model);
@@ -1824,7 +1824,7 @@ QModelIndex QFileDialogPrivate::rootIndex() const {
 
 QAbstractItemView *QFileDialogPrivate::currentView() const {
     if (!qFileDialogUi->stackedWidget)
-        return 0;
+        return nullptr;
     if (qFileDialogUi->stackedWidget->currentWidget() == qFileDialogUi->listView->parent())
         return qFileDialogUi->listView;
     return qFileDialogUi->treeView;
@@ -2038,7 +2038,7 @@ QAbstractItemDelegate *QFileDialog::itemDelegate() const
 {
     Q_D(const QFileDialog);
     if (!d->usingWidgets())
-        return 0;
+        return nullptr;
     return d->qFileDialogUi->listView->itemDelegate();
 }
 
@@ -2776,7 +2776,7 @@ void QFileDialog::done(int result)
     if (d->receiverToDisconnectOnClose) {
         disconnect(this, d->signalToDisconnectOnClose,
                    d->receiverToDisconnectOnClose, d->memberToDisconnectOnClose);
-        d->receiverToDisconnectOnClose = 0;
+        d->receiverToDisconnectOnClose = nullptr;
     }
     d->memberToDisconnectOnClose.clear();
     d->signalToDisconnectOnClose.clear();
@@ -3015,7 +3015,7 @@ void QFileDialogPrivate::init(const QUrl &directory, const QString &nameFilter,
     }
 
     q->setAcceptMode(QFileDialog::AcceptOpen);
-    nativeDialogInUse = platformFileDialogHelper() != 0;
+    nativeDialogInUse = platformFileDialogHelper() != nullptr;
     if (!nativeDialogInUse)
         createWidgets();
     q->setFileMode(QFileDialog::AnyFile);
@@ -3273,7 +3273,7 @@ void QFileDialog::setProxyModel(QAbstractProxyModel *proxyModel)
             this, SLOT(_q_rowsInserted(QModelIndex)));
     }
 
-    if (proxyModel != 0) {
+    if (proxyModel != nullptr) {
         proxyModel->setParent(this);
         d->proxyModel = proxyModel;
         proxyModel->setSourceModel(d->model);
@@ -3286,13 +3286,13 @@ void QFileDialog::setProxyModel(QAbstractProxyModel *proxyModel)
         connect(d->proxyModel, SIGNAL(rowsInserted(QModelIndex,int,int)),
             this, SLOT(_q_rowsInserted(QModelIndex)));
     } else {
-        d->proxyModel = 0;
+        d->proxyModel = nullptr;
         d->qFileDialogUi->listView->setModel(d->model);
         d->qFileDialogUi->treeView->setModel(d->model);
 #if QT_CONFIG(fscompleter)
         d->completer->setModel(d->model);
         d->completer->sourceModel = d->model;
-        d->completer->proxyModel = 0;
+        d->completer->proxyModel = nullptr;
 #endif
         connect(d->model, SIGNAL(rowsInserted(QModelIndex,int,int)),
             this, SLOT(_q_rowsInserted(QModelIndex)));
@@ -3330,27 +3330,27 @@ QAbstractProxyModel *QFileDialog::proxyModel() const
 void QFileDialogPrivate::createToolButtons()
 {
     Q_Q(QFileDialog);
-    qFileDialogUi->backButton->setIcon(q->style()->standardIcon(QStyle::SP_ArrowBack, 0, q));
+    qFileDialogUi->backButton->setIcon(q->style()->standardIcon(QStyle::SP_ArrowBack, nullptr, q));
     qFileDialogUi->backButton->setAutoRaise(true);
     qFileDialogUi->backButton->setEnabled(false);
     QObject::connect(qFileDialogUi->backButton, SIGNAL(clicked()), q, SLOT(_q_navigateBackward()));
 
-    qFileDialogUi->forwardButton->setIcon(q->style()->standardIcon(QStyle::SP_ArrowForward, 0, q));
+    qFileDialogUi->forwardButton->setIcon(q->style()->standardIcon(QStyle::SP_ArrowForward, nullptr, q));
     qFileDialogUi->forwardButton->setAutoRaise(true);
     qFileDialogUi->forwardButton->setEnabled(false);
     QObject::connect(qFileDialogUi->forwardButton, SIGNAL(clicked()), q, SLOT(_q_navigateForward()));
 
-    qFileDialogUi->toParentButton->setIcon(q->style()->standardIcon(QStyle::SP_FileDialogToParent, 0, q));
+    qFileDialogUi->toParentButton->setIcon(q->style()->standardIcon(QStyle::SP_FileDialogToParent, nullptr, q));
     qFileDialogUi->toParentButton->setAutoRaise(true);
     qFileDialogUi->toParentButton->setEnabled(false);
     QObject::connect(qFileDialogUi->toParentButton, SIGNAL(clicked()), q, SLOT(_q_navigateToParent()));
 
-    qFileDialogUi->listModeButton->setIcon(q->style()->standardIcon(QStyle::SP_FileDialogListView, 0, q));
+    qFileDialogUi->listModeButton->setIcon(q->style()->standardIcon(QStyle::SP_FileDialogListView, nullptr, q));
     qFileDialogUi->listModeButton->setAutoRaise(true);
     qFileDialogUi->listModeButton->setDown(true);
     QObject::connect(qFileDialogUi->listModeButton, SIGNAL(clicked()), q, SLOT(_q_showListView()));
 
-    qFileDialogUi->detailModeButton->setIcon(q->style()->standardIcon(QStyle::SP_FileDialogDetailedView, 0, q));
+    qFileDialogUi->detailModeButton->setIcon(q->style()->standardIcon(QStyle::SP_FileDialogDetailedView, nullptr, q));
     qFileDialogUi->detailModeButton->setAutoRaise(true);
     QObject::connect(qFileDialogUi->detailModeButton, SIGNAL(clicked()), q, SLOT(_q_showDetailsView()));
 
@@ -3361,7 +3361,7 @@ void QFileDialogPrivate::createToolButtons()
     qFileDialogUi->forwardButton->setFixedSize(toolSize);
     qFileDialogUi->toParentButton->setFixedSize(toolSize);
 
-    qFileDialogUi->newFolderButton->setIcon(q->style()->standardIcon(QStyle::SP_FileDialogNewFolder, 0, q));
+    qFileDialogUi->newFolderButton->setIcon(q->style()->standardIcon(QStyle::SP_FileDialogNewFolder, nullptr, q));
     qFileDialogUi->newFolderButton->setFixedSize(toolSize);
     qFileDialogUi->newFolderButton->setAutoRaise(true);
     qFileDialogUi->newFolderButton->setEnabled(false);
@@ -3598,7 +3598,7 @@ void QFileDialogPrivate::_q_showContextMenu(const QPoint &position)
     Q_UNUSED(position);
 #else
     Q_Q(QFileDialog);
-    QAbstractItemView *view = 0;
+    QAbstractItemView *view = nullptr;
     if (q->viewMode() == QFileDialog::Detail)
         view = qFileDialogUi->treeView;
     else
diff --git a/src/widgets/dialogs/qfilesystemmodel.cpp b/src/widgets/dialogs/qfilesystemmodel.cpp
index 79a7c23e0d..914c845565 100644
--- a/src/widgets/dialogs/qfilesystemmodel.cpp
+++ b/src/widgets/dialogs/qfilesystemmodel.cpp
@@ -586,9 +586,9 @@ QModelIndex QFileSystemModel::parent(const QModelIndex &index) const
         return QModelIndex();
 
     QFileSystemModelPrivate::QFileSystemNode *indexNode = d->node(index);
-    Q_ASSERT(indexNode != 0);
+    Q_ASSERT(indexNode != nullptr);
     QFileSystemModelPrivate::QFileSystemNode *parentNode = indexNode->parent;
-    if (parentNode == 0 || parentNode == &d->root)
+    if (parentNode == nullptr || parentNode == &d->root)
         return QModelIndex();
 
     // get the parent's row
@@ -608,7 +608,7 @@ QModelIndex QFileSystemModel::parent(const QModelIndex &index) const
 QModelIndex QFileSystemModelPrivate::index(const QFileSystemModelPrivate::QFileSystemNode *node, int column) const
 {
     Q_Q(const QFileSystemModel);
-    QFileSystemModelPrivate::QFileSystemNode *parentNode = (node ? node->parent : 0);
+    QFileSystemModelPrivate::QFileSystemNode *parentNode = (node ? node->parent : nullptr);
     if (node == &root || !parentNode)
         return QModelIndex();
 
diff --git a/src/widgets/dialogs/qfontdialog.cpp b/src/widgets/dialogs/qfontdialog.cpp
index 3da829d328..fe8f88d64f 100644
--- a/src/widgets/dialogs/qfontdialog.cpp
+++ b/src/widgets/dialogs/qfontdialog.cpp
@@ -276,7 +276,7 @@ void QFontDialogPrivate::init()
        mainGrid->setColumnMinimumWidth(3, spacing);
 
        int margin = 0;
-       mainGrid->getContentsMargins(0, 0, 0, &margin);
+       mainGrid->getContentsMargins(nullptr, nullptr, nullptr, &margin);
 
        mainGrid->setRowMinimumHeight(3, margin);
        mainGrid->setRowMinimumHeight(6, 2);
@@ -435,7 +435,7 @@ bool QFontDialog::eventFilter(QObject *o , QEvent *e)
             QCoreApplication::sendEvent(d->sizeList, k);
 
             if (ci != d->sizeList->currentItem()
-                    && style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, 0, this))
+                    && style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, nullptr, this))
                 d->sizeEdit->selectAll();
             return true;
         } else if ((o == d->familyList || o == d->styleList) &&
@@ -445,7 +445,7 @@ bool QFontDialog::eventFilter(QObject *o , QEvent *e)
             return true;
         }
     } else if (e->type() == QEvent::FocusIn
-               && style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, 0, this)) {
+               && style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, nullptr, this)) {
         if (o == d->familyList)
             d->familyEdit->selectAll();
         else if (o == d->styleList)
@@ -550,7 +550,7 @@ void QFontDialogPrivate::updateFamilies()
     else
         familyList->setCurrentItem(0);
     familyEdit->setText(familyList->currentText());
-    if (q->style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, 0, q)
+    if (q->style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, nullptr, q)
             && familyList->hasFocus())
         familyEdit->selectAll();
 
@@ -602,7 +602,7 @@ void QFontDialogPrivate::updateStyles()
         }
 
         styleEdit->setText(styleList->currentText());
-        if (q->style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, 0, q)
+        if (q->style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, nullptr, q)
                 && styleList->hasFocus())
             styleEdit->selectAll();
 
@@ -641,7 +641,7 @@ void QFontDialogPrivate::updateSizes()
 
         const QSignalBlocker blocker(sizeEdit);
         sizeEdit->setText((smoothScalable ? QString::number(size) : sizeList->currentText()));
-        if (q->style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, 0, q)
+        if (q->style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, nullptr, q)
                 && sizeList->hasFocus())
             sizeEdit->selectAll();
     } else {
@@ -692,7 +692,7 @@ void QFontDialogPrivate::_q_familyHighlighted(int i)
     Q_Q(QFontDialog);
     family = familyList->text(i);
     familyEdit->setText(family);
-    if (q->style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, 0, q)
+    if (q->style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, nullptr, q)
             && familyList->hasFocus())
         familyEdit->selectAll();
 
@@ -709,7 +709,7 @@ void QFontDialogPrivate::_q_styleHighlighted(int index)
     Q_Q(QFontDialog);
     QString s = styleList->text(index);
     styleEdit->setText(s);
-    if (q->style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, 0, q)
+    if (q->style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, nullptr, q)
             && styleList->hasFocus())
         styleEdit->selectAll();
 
@@ -728,7 +728,7 @@ void QFontDialogPrivate::_q_sizeHighlighted(int index)
     Q_Q(QFontDialog);
     QString s = sizeList->text(index);
     sizeEdit->setText(s);
-    if (q->style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, 0, q)
+    if (q->style()->styleHint(QStyle::SH_FontDialog_SelectAssociatedText, nullptr, q)
             && sizeEdit->hasFocus())
         sizeEdit->selectAll();
 
@@ -1019,7 +1019,7 @@ void QFontDialog::done(int result)
     if (d->receiverToDisconnectOnClose) {
         disconnect(this, SIGNAL(fontSelected(QFont)),
                    d->receiverToDisconnectOnClose, d->memberToDisconnectOnClose);
-        d->receiverToDisconnectOnClose = 0;
+        d->receiverToDisconnectOnClose = nullptr;
     }
     d->memberToDisconnectOnClose.clear();
 }
diff --git a/src/widgets/dialogs/qinputdialog.cpp b/src/widgets/dialogs/qinputdialog.cpp
index 3cfe8367e0..1cb4be0682 100644
--- a/src/widgets/dialogs/qinputdialog.cpp
+++ b/src/widgets/dialogs/qinputdialog.cpp
@@ -138,7 +138,7 @@ class QInputDialogDoubleSpinBox : public QDoubleSpinBox
     Q_OBJECT
 
 public:
-    QInputDialogDoubleSpinBox(QWidget *parent = 0)
+    QInputDialogDoubleSpinBox(QWidget *parent = nullptr)
         : QDoubleSpinBox(parent) {
         connect(lineEdit(), SIGNAL(textChanged(QString)), this, SLOT(notifyTextChanged()));
         connect(this, SIGNAL(editingFinished()), this, SLOT(notifyTextChanged()));
@@ -171,7 +171,7 @@ private:
 class QInputDialogListView : public QListView
 {
 public:
-    QInputDialogListView(QWidget *parent = 0) : QListView(parent) {}
+    QInputDialogListView(QWidget *parent = nullptr) : QListView(parent) {}
     QVariant inputMethodQuery(Qt::InputMethodQuery query) const override
     {
         if (query == Qt::ImEnabled)
@@ -223,8 +223,8 @@ public:
 };
 
 QInputDialogPrivate::QInputDialogPrivate()
-    : label(0), buttonBox(0), lineEdit(0), plainTextEdit(0), intSpinBox(0), doubleSpinBox(0),
-      comboBox(0), listView(0), inputWidget(0), mainLayout(0)
+    : label(nullptr), buttonBox(nullptr), lineEdit(nullptr), plainTextEdit(nullptr), intSpinBox(nullptr), doubleSpinBox(nullptr),
+      comboBox(nullptr), listView(nullptr), inputWidget(nullptr), mainLayout(nullptr)
 {
 }
 
@@ -1174,7 +1174,7 @@ void QInputDialog::done(int result)
     if (d->receiverToDisconnectOnClose) {
         disconnect(this, signalForMember(d->memberToDisconnectOnClose),
                    d->receiverToDisconnectOnClose, d->memberToDisconnectOnClose);
-        d->receiverToDisconnectOnClose = 0;
+        d->receiverToDisconnectOnClose = nullptr;
     }
     d->memberToDisconnectOnClose.clear();
 }
diff --git a/src/widgets/dialogs/qmessagebox.cpp b/src/widgets/dialogs/qmessagebox.cpp
index 8dad212692..17d199cb4f 100644
--- a/src/widgets/dialogs/qmessagebox.cpp
+++ b/src/widgets/dialogs/qmessagebox.cpp
@@ -97,7 +97,7 @@ public:
     class TextEdit : public QTextEdit
     {
     public:
-        TextEdit(QWidget *parent=0) : QTextEdit(parent) { }
+        TextEdit(QWidget *parent=nullptr) : QTextEdit(parent) { }
 #ifndef QT_NO_CONTEXTMENU
         void contextMenuEvent(QContextMenuEvent * e) override
         {
@@ -108,7 +108,7 @@ public:
 #endif // QT_NO_CONTEXTMENU
     };
 
-    QMessageBoxDetailsText(QWidget *parent=0)
+    QMessageBoxDetailsText(QWidget *parent=nullptr)
         : QWidget(parent)
         , copyAvailable(false)
     {
@@ -197,12 +197,12 @@ class QMessageBoxPrivate : public QDialogPrivate
     Q_DECLARE_PUBLIC(QMessageBox)
 
 public:
-    QMessageBoxPrivate() : escapeButton(0), defaultButton(0), checkbox(0), clickedButton(0), detailsButton(0),
+    QMessageBoxPrivate() : escapeButton(nullptr), defaultButton(nullptr), checkbox(nullptr), clickedButton(nullptr), detailsButton(nullptr),
 #if QT_CONFIG(textedit)
-                           detailsText(0),
+                           detailsText(nullptr),
 #endif
                            compatMode(false), autoAddOkButton(true),
-                           detectedEscapeButton(0), informativeLabel(0),
+                           detectedEscapeButton(nullptr), informativeLabel(nullptr),
                            options(QMessageDialogOptions::create()) { }
 
     void init(const QString &title = QString(), const QString &text = QString());
@@ -274,7 +274,7 @@ void QMessageBoxPrivate::init(const QString &title, const QString &text)
 
     label = new QLabel;
     label->setObjectName(QLatin1String("qt_msgbox_label"));
-    label->setTextInteractionFlags(Qt::TextInteractionFlags(q->style()->styleHint(QStyle::SH_MessageBox_TextInteractionFlags, 0, q)));
+    label->setTextInteractionFlags(Qt::TextInteractionFlags(q->style()->styleHint(QStyle::SH_MessageBox_TextInteractionFlags, nullptr, q)));
     label->setAlignment(Qt::AlignVCenter | Qt::AlignLeft);
     label->setOpenExternalLinks(true);
     iconLabel = new QLabel(q);
@@ -283,7 +283,7 @@ void QMessageBoxPrivate::init(const QString &title, const QString &text)
 
     buttonBox = new QDialogButtonBox;
     buttonBox->setObjectName(QLatin1String("qt_msgbox_buttonbox"));
-    buttonBox->setCenterButtons(q->style()->styleHint(QStyle::SH_MessageBox_CenterButtons, 0, q));
+    buttonBox->setCenterButtons(q->style()->styleHint(QStyle::SH_MessageBox_CenterButtons, nullptr, q));
     QObject::connect(buttonBox, SIGNAL(clicked(QAbstractButton*)),
                      q, SLOT(_q_buttonClicked(QAbstractButton*)));
     setupLayout();
@@ -927,9 +927,9 @@ void QMessageBox::removeButton(QAbstractButton *button)
     Q_D(QMessageBox);
     d->customButtonList.removeAll(button);
     if (d->escapeButton == button)
-        d->escapeButton = 0;
+        d->escapeButton = nullptr;
     if (d->defaultButton == button)
-        d->defaultButton = 0;
+        d->defaultButton = nullptr;
     d->buttonBox->removeButton(button);
     d->updateSize();
 }
@@ -952,9 +952,9 @@ void QMessageBox::setStandardButtons(StandardButtons buttons)
 
     QList<QAbstractButton *> buttonList = d->buttonBox->buttons();
     if (!buttonList.contains(d->escapeButton))
-        d->escapeButton = 0;
+        d->escapeButton = nullptr;
     if (!buttonList.contains(d->defaultButton))
-        d->defaultButton = 0;
+        d->defaultButton = nullptr;
     d->autoAddOkButton = false;
     d->updateSize();
 }
@@ -1081,7 +1081,7 @@ void QMessageBoxPrivate::detectEscapeButton()
     for (auto *button : buttons) {
         if (buttonBox->buttonRole(button) == QDialogButtonBox::RejectRole) {
             if (detectedEscapeButton) { // already detected!
-                detectedEscapeButton = 0;
+                detectedEscapeButton = nullptr;
                 break;
             }
             detectedEscapeButton = button;
@@ -1094,7 +1094,7 @@ void QMessageBoxPrivate::detectEscapeButton()
     for (auto *button : buttons) {
         if (buttonBox->buttonRole(button) == QDialogButtonBox::NoRole) {
             if (detectedEscapeButton) { // already detected!
-                detectedEscapeButton = 0;
+                detectedEscapeButton = nullptr;
                 break;
             }
             detectedEscapeButton = button;
@@ -1189,7 +1189,7 @@ void QMessageBox::setCheckBox(QCheckBox *cb)
         d->checkbox->hide();
         layout()->removeWidget(d->checkbox);
         if (d->checkbox->parentWidget() == this) {
-            d->checkbox->setParent(0);
+            d->checkbox->setParent(nullptr);
             d->checkbox->deleteLater();
         }
     }
@@ -1433,9 +1433,9 @@ void QMessageBox::changeEvent(QEvent *ev)
     {
         if (d->icon != NoIcon)
             setIcon(d->icon);
-        Qt::TextInteractionFlags flags(style()->styleHint(QStyle::SH_MessageBox_TextInteractionFlags, 0, this));
+        Qt::TextInteractionFlags flags(style()->styleHint(QStyle::SH_MessageBox_TextInteractionFlags, nullptr, this));
         d->label->setTextInteractionFlags(flags);
-        d->buttonBox->setCenterButtons(style()->styleHint(QStyle::SH_MessageBox_CenterButtons, 0, this));
+        d->buttonBox->setCenterButtons(style()->styleHint(QStyle::SH_MessageBox_CenterButtons, nullptr, this));
         if (d->informativeLabel)
             d->informativeLabel->setTextInteractionFlags(flags);
         Q_FALLTHROUGH();
@@ -1624,7 +1624,7 @@ static QMessageBox::StandardButton showNewMessageBox(QWidget *parent,
 
     QMessageBox msgBox(icon, title, text, QMessageBox::NoButton, parent);
     QDialogButtonBox *buttonBox = msgBox.findChild<QDialogButtonBox*>();
-    Q_ASSERT(buttonBox != 0);
+    Q_ASSERT(buttonBox != nullptr);
 
     uint mask = QMessageBox::FirstButton;
     while (mask <= QMessageBox::LastButton) {
@@ -2001,7 +2001,7 @@ QAbstractButton *QMessageBoxPrivate::abstractButtonForId(int id) const
     if (result)
         return result;
     if (id & QMessageBox::FlagMask)    // for compatibility with Qt 4.0/4.1 (even if it is silly)
-        return 0;
+        return nullptr;
     return q->button(newButton(id));
 }
 
@@ -2522,13 +2522,13 @@ void QMessageBox::setDetailedText(const QString &text)
             d->detailsText->hide();
             d->detailsText->deleteLater();
         }
-        d->detailsText = 0;
+        d->detailsText = nullptr;
         removeButton(d->detailsButton);
         if (d->detailsButton) {
             d->detailsButton->hide();
             d->detailsButton->deleteLater();
         }
-        d->detailsButton = 0;
+        d->detailsButton = nullptr;
     } else {
         if (!d->detailsText) {
             d->detailsText = new QMessageBoxDetailsText(this);
@@ -2577,12 +2577,12 @@ void QMessageBox::setInformativeText(const QString &text)
             d->informativeLabel->hide();
             d->informativeLabel->deleteLater();
         }
-        d->informativeLabel = 0;
+        d->informativeLabel = nullptr;
     } else {
         if (!d->informativeLabel) {
             QLabel *label = new QLabel;
             label->setObjectName(QLatin1String("qt_msgbox_informativelabel"));
-            label->setTextInteractionFlags(Qt::TextInteractionFlags(style()->styleHint(QStyle::SH_MessageBox_TextInteractionFlags, 0, this)));
+            label->setTextInteractionFlags(Qt::TextInteractionFlags(style()->styleHint(QStyle::SH_MessageBox_TextInteractionFlags, nullptr, this)));
             label->setAlignment(Qt::AlignTop | Qt::AlignLeft);
             label->setOpenExternalLinks(true);
             label->setWordWrap(true);
@@ -2644,20 +2644,20 @@ void QMessageBox::setWindowModality(Qt::WindowModality windowModality)
 QPixmap QMessageBoxPrivate::standardIcon(QMessageBox::Icon icon, QMessageBox *mb)
 {
     QStyle *style = mb ? mb->style() : QApplication::style();
-    int iconSize = style->pixelMetric(QStyle::PM_MessageBoxIconSize, 0, mb);
+    int iconSize = style->pixelMetric(QStyle::PM_MessageBoxIconSize, nullptr, mb);
     QIcon tmpIcon;
     switch (icon) {
     case QMessageBox::Information:
-        tmpIcon = style->standardIcon(QStyle::SP_MessageBoxInformation, 0, mb);
+        tmpIcon = style->standardIcon(QStyle::SP_MessageBoxInformation, nullptr, mb);
         break;
     case QMessageBox::Warning:
-        tmpIcon = style->standardIcon(QStyle::SP_MessageBoxWarning, 0, mb);
+        tmpIcon = style->standardIcon(QStyle::SP_MessageBoxWarning, nullptr, mb);
         break;
     case QMessageBox::Critical:
-        tmpIcon = style->standardIcon(QStyle::SP_MessageBoxCritical, 0, mb);
+        tmpIcon = style->standardIcon(QStyle::SP_MessageBoxCritical, nullptr, mb);
         break;
     case QMessageBox::Question:
-        tmpIcon = style->standardIcon(QStyle::SP_MessageBoxQuestion, 0, mb);
+        tmpIcon = style->standardIcon(QStyle::SP_MessageBoxQuestion, nullptr, mb);
     default:
         break;
     }
@@ -2739,7 +2739,7 @@ void QMessageBoxPrivate::helperDone(QDialog::DialogCode code, QPlatformDialogHel
 
 QPixmap QMessageBox::standardIcon(Icon icon)
 {
-    return QMessageBoxPrivate::standardIcon(icon, 0);
+    return QMessageBoxPrivate::standardIcon(icon, nullptr);
 }
 
 /*!
diff --git a/src/widgets/dialogs/qprogressdialog.cpp b/src/widgets/dialogs/qprogressdialog.cpp
index 189dcd2989..94d3928c8b 100644
--- a/src/widgets/dialogs/qprogressdialog.cpp
+++ b/src/widgets/dialogs/qprogressdialog.cpp
@@ -65,13 +65,13 @@ class QProgressDialogPrivate : public QDialogPrivate
     Q_DECLARE_PUBLIC(QProgressDialog)
 
 public:
-    QProgressDialogPrivate() : label(0), cancel(0), bar(0),
+    QProgressDialogPrivate() : label(nullptr), cancel(nullptr), bar(nullptr),
         shown_once(false),
         cancellation_flag(false),
         setValue_called(false),
         showTime(defaultShowTime),
 #ifndef QT_NO_SHORTCUT
-        escapeShortcut(0),
+        escapeShortcut(nullptr),
 #endif
         useDefaultCancelText(false)
     {
@@ -112,7 +112,7 @@ void QProgressDialogPrivate::init(const QString &labelText, const QString &cance
     label = new QLabel(labelText, q);
     bar = new QProgressBar(q);
     bar->setRange(min, max);
-    int align = q->style()->styleHint(QStyle::SH_ProgressDialog_TextLabelAlignment, 0, q);
+    int align = q->style()->styleHint(QStyle::SH_ProgressDialog_TextLabelAlignment, nullptr, q);
     label->setAlignment(Qt::Alignment(align));
     autoClose = true;
     autoReset = true;
@@ -132,12 +132,12 @@ void QProgressDialogPrivate::init(const QString &labelText, const QString &cance
 void QProgressDialogPrivate::layout()
 {
     Q_Q(QProgressDialog);
-    int sp = q->style()->pixelMetric(QStyle::PM_LayoutVerticalSpacing, 0, q);
-    int mb = q->style()->pixelMetric(QStyle::PM_LayoutBottomMargin, 0, q);
-    int ml = qMin(q->width() / 10, q->style()->pixelMetric(QStyle::PM_LayoutLeftMargin, 0, q));
-    int mr = qMin(q->width() / 10, q->style()->pixelMetric(QStyle::PM_LayoutRightMargin, 0, q));
+    int sp = q->style()->pixelMetric(QStyle::PM_LayoutVerticalSpacing, nullptr, q);
+    int mb = q->style()->pixelMetric(QStyle::PM_LayoutBottomMargin, nullptr, q);
+    int ml = qMin(q->width() / 10, q->style()->pixelMetric(QStyle::PM_LayoutLeftMargin, nullptr, q));
+    int mr = qMin(q->width() / 10, q->style()->pixelMetric(QStyle::PM_LayoutRightMargin, nullptr, q));
     const bool centered =
-        bool(q->style()->styleHint(QStyle::SH_ProgressDialog_CenterCancelButton, 0, q));
+        bool(q->style()->styleHint(QStyle::SH_ProgressDialog_CenterCancelButton, nullptr, q));
 
     int additionalSpacing = 0;
     QSize cs = cancel ? cancel->sizeHint() : QSize(0,0);
@@ -188,7 +188,7 @@ void QProgressDialogPrivate::_q_disconnectOnClose()
     if (receiverToDisconnectOnClose) {
         QObject::disconnect(q, SIGNAL(canceled()), receiverToDisconnectOnClose,
                             memberToDisconnectOnClose);
-        receiverToDisconnectOnClose = 0;
+        receiverToDisconnectOnClose = nullptr;
     }
     memberToDisconnectOnClose.clear();
 }
@@ -418,7 +418,7 @@ void QProgressDialog::setCancelButton(QPushButton *cancelButton)
     } else {
 #ifndef QT_NO_SHORTCUT
         delete d->escapeShortcut;
-        d->escapeShortcut = 0;
+        d->escapeShortcut = nullptr;
 #endif
     }
     d->adoptChildWidget(cancelButton);
@@ -450,7 +450,7 @@ void QProgressDialogPrivate::setCancelButtonText(const QString &cancelButtonText
             q->setCancelButton(new QPushButton(cancelButtonText, q));
         }
     } else {
-        q->setCancelButton(0);
+        q->setCancelButton(nullptr);
     }
     ensureSizeIsAtLeastSizeHint();
 }
diff --git a/src/widgets/dialogs/qsidebar.cpp b/src/widgets/dialogs/qsidebar.cpp
index 2c8c66e1e2..dfb707eda0 100644
--- a/src/widgets/dialogs/qsidebar.cpp
+++ b/src/widgets/dialogs/qsidebar.cpp
@@ -73,7 +73,7 @@ void QSideBarDelegate::initStyleOption(QStyleOptionViewItem *option,
 
     Example usage: File dialog sidebar and combo box
  */
-QUrlModel::QUrlModel(QObject *parent) : QStandardItemModel(parent), showFullPath(false), fileSystemModel(0)
+QUrlModel::QUrlModel(QObject *parent) : QStandardItemModel(parent), showFullPath(false), fileSystemModel(nullptr)
 {
 }
 
@@ -298,7 +298,7 @@ void QUrlModel::setFileSystemModel(QFileSystemModel *model)
 {
     if (model == fileSystemModel)
         return;
-    if (fileSystemModel != 0) {
+    if (fileSystemModel != nullptr) {
         disconnect(model, SIGNAL(dataChanged(QModelIndex,QModelIndex)),
             this, SLOT(dataChanged(QModelIndex,QModelIndex)));
         disconnect(model, SIGNAL(layoutChanged()),
@@ -307,7 +307,7 @@ void QUrlModel::setFileSystemModel(QFileSystemModel *model)
             this, SLOT(layoutChanged()));
     }
     fileSystemModel = model;
-    if (fileSystemModel != 0) {
+    if (fileSystemModel != nullptr) {
         connect(model, SIGNAL(dataChanged(QModelIndex,QModelIndex)),
             this, SLOT(dataChanged(QModelIndex,QModelIndex)));
         connect(model, SIGNAL(layoutChanged()),
diff --git a/src/widgets/dialogs/qwizard.cpp b/src/widgets/dialogs/qwizard.cpp
index 7c4a473976..a4789f40b1 100644
--- a/src/widgets/dialogs/qwizard.cpp
+++ b/src/widgets/dialogs/qwizard.cpp
@@ -115,7 +115,7 @@ static QWidget *iWantTheFocus(QWidget *ancestor)
                 return candidate;
         }
     }
-    return 0;
+    return nullptr;
 }
 
 static bool objectInheritsXAndXIsCloserThanY(const QObject *object, const QByteArray &classX,
@@ -165,7 +165,7 @@ static const char *changed_signal(int which)
     };
     Q_STATIC_ASSERT(7 == NFallbackDefaultProperties);
     Q_UNREACHABLE();
-    return 0;
+    return nullptr;
 }
 
 class QWizardDefaultProperty
@@ -286,9 +286,9 @@ class QWizardHeader : public QWidget
 public:
     enum RulerType { Ruler };
 
-    inline QWizardHeader(RulerType /* ruler */, QWidget *parent = 0)
+    inline QWizardHeader(RulerType /* ruler */, QWidget *parent = nullptr)
         : QWidget(parent) { setFixedHeight(2); }
-    QWizardHeader(QWidget *parent = 0);
+    QWizardHeader(QWidget *parent = nullptr);
 
     void setup(const QWizardLayoutInfo &info, const QString &title,
                const QString &subTitle, const QPixmap &logo, const QPixmap &banner,
@@ -438,7 +438,7 @@ void QWizardHeader::paintEvent(QPaintEvent * /* event */)
 class QWizardRuler : public QWizardHeader
 {
 public:
-    inline QWizardRuler(QWidget *parent = 0)
+    inline QWizardRuler(QWidget *parent = nullptr)
         : QWizardHeader(Ruler, parent) {}
 };
 
@@ -684,7 +684,7 @@ void QWizardPrivate::init()
     std::fill(btns, btns + QWizard::NButtons, nullptr);
 
     antiFlickerWidget = new QWizardAntiFlickerWidget(q, this);
-    wizStyle = QWizard::WizardStyle(q->style()->styleHint(QStyle::SH_WizardStyle, 0, q));
+    wizStyle = QWizard::WizardStyle(q->style()->styleHint(QStyle::SH_WizardStyle, nullptr, q));
     if (wizStyle == QWizard::MacStyle) {
         opts = (QWizard::NoDefaultButton | QWizard::NoCancelButton);
     } else if (wizStyle == QWizard::ModernStyle) {
@@ -836,7 +836,7 @@ void QWizardPrivate::switchToPage(int newId, Direction direction)
         newPage && newPage->isCommitPage() ? QWizard::CommitButton : QWizard::NextButton;
     QAbstractButton *nextOrFinishButton =
         btns[canContinue ? nextOrCommit : QWizard::FinishButton];
-    QWidget *candidate = 0;
+    QWidget *candidate = nullptr;
 
     /*
         If there is no default button and the Next or Finish button
@@ -887,7 +887,7 @@ static const char * buttonSlots(QWizard::WizardButton which)
     case QWizard::NoButton:
         Q_UNREACHABLE();
     };
-    return 0;
+    return nullptr;
 };
 
 QWizardLayoutInfo QWizardPrivate::layoutInfoForCurrentPage()
@@ -898,14 +898,14 @@ QWizardLayoutInfo QWizardPrivate::layoutInfoForCurrentPage()
     QWizardLayoutInfo info;
 
     const int layoutHorizontalSpacing = style->pixelMetric(QStyle::PM_LayoutHorizontalSpacing);
-    info.topLevelMarginLeft = style->pixelMetric(QStyle::PM_LayoutLeftMargin, 0, q);
-    info.topLevelMarginRight = style->pixelMetric(QStyle::PM_LayoutRightMargin, 0, q);
-    info.topLevelMarginTop = style->pixelMetric(QStyle::PM_LayoutTopMargin, 0, q);
-    info.topLevelMarginBottom = style->pixelMetric(QStyle::PM_LayoutBottomMargin, 0, q);
-    info.childMarginLeft = style->pixelMetric(QStyle::PM_LayoutLeftMargin, 0, titleLabel);
-    info.childMarginRight = style->pixelMetric(QStyle::PM_LayoutRightMargin, 0, titleLabel);
-    info.childMarginTop = style->pixelMetric(QStyle::PM_LayoutTopMargin, 0, titleLabel);
-    info.childMarginBottom = style->pixelMetric(QStyle::PM_LayoutBottomMargin, 0, titleLabel);
+    info.topLevelMarginLeft = style->pixelMetric(QStyle::PM_LayoutLeftMargin, nullptr, q);
+    info.topLevelMarginRight = style->pixelMetric(QStyle::PM_LayoutRightMargin, nullptr, q);
+    info.topLevelMarginTop = style->pixelMetric(QStyle::PM_LayoutTopMargin, nullptr, q);
+    info.topLevelMarginBottom = style->pixelMetric(QStyle::PM_LayoutBottomMargin, nullptr, q);
+    info.childMarginLeft = style->pixelMetric(QStyle::PM_LayoutLeftMargin, nullptr, titleLabel);
+    info.childMarginRight = style->pixelMetric(QStyle::PM_LayoutRightMargin, nullptr, titleLabel);
+    info.childMarginTop = style->pixelMetric(QStyle::PM_LayoutTopMargin, nullptr, titleLabel);
+    info.childMarginBottom = style->pixelMetric(QStyle::PM_LayoutBottomMargin, nullptr, titleLabel);
     info.hspacing = (layoutHorizontalSpacing == -1)
         ? style->layoutSpacing(QSizePolicy::DefaultType, QSizePolicy::DefaultType, Qt::Horizontal)
         : layoutHorizontalSpacing;
@@ -959,7 +959,7 @@ void QWizardPrivate::recreateLayout(const QWizardLayoutInfo &info)
     for (int i = mainLayout->count() - 1; i >= 0; --i) {
         QLayoutItem *item = mainLayout->takeAt(i);
         if (item->layout()) {
-            item->layout()->setParent(0);
+            item->layout()->setParent(nullptr);
         } else {
             delete item;
         }
@@ -2281,7 +2281,7 @@ void QWizard::removePage(int id)
 {
     Q_D(QWizard);
 
-    QWizardPage *removedPage = 0;
+    QWizardPage *removedPage = nullptr;
 
     // update startItem accordingly
     if (d->pageMap.count() > 0) { // only if we have any pages
@@ -2792,7 +2792,7 @@ QAbstractButton *QWizard::button(WizardButton which) const
         return d->vistaHelper->backButton();
 #endif
     if (!d->ensureButton(which))
-        return 0;
+        return nullptr;
     return d->btns[which];
 }
 
diff --git a/src/widgets/effects/qgraphicseffect.cpp b/src/widgets/effects/qgraphicseffect.cpp
index 94188f3485..2eb74ce2a8 100644
--- a/src/widgets/effects/qgraphicseffect.cpp
+++ b/src/widgets/effects/qgraphicseffect.cpp
@@ -415,7 +415,7 @@ QGraphicsEffect::QGraphicsEffect(QGraphicsEffectPrivate &dd, QObject *parent)
 QGraphicsEffect::~QGraphicsEffect()
 {
     Q_D(QGraphicsEffect);
-    d->setGraphicsEffectSource(0);
+    d->setGraphicsEffectSource(nullptr);
 }
 
 /*!
diff --git a/src/widgets/effects/qpixmapfilter.cpp b/src/widgets/effects/qpixmapfilter.cpp
index e1e8175423..637c9c6aba 100644
--- a/src/widgets/effects/qpixmapfilter.cpp
+++ b/src/widgets/effects/qpixmapfilter.cpp
@@ -208,7 +208,7 @@ QRectF QPixmapFilter::boundingRectFor(const QRectF &rect) const
 class QPixmapConvolutionFilterPrivate : public QPixmapFilterPrivate
 {
 public:
-    QPixmapConvolutionFilterPrivate(): convolutionKernel(0), kernelWidth(0), kernelHeight(0), convoluteAlpha(false) {}
+    QPixmapConvolutionFilterPrivate(): convolutionKernel(nullptr), kernelWidth(0), kernelHeight(0), convoluteAlpha(false) {}
     ~QPixmapConvolutionFilterPrivate() {
         delete[] convolutionKernel;
     }
@@ -424,7 +424,7 @@ void QPixmapConvolutionFilter::draw(QPainter *painter, const QPointF &p, const Q
 
     // raster implementation
 
-    QImage *target = 0;
+    QImage *target = nullptr;
     if (painter->paintEngine()->paintDevice()->devType() == QInternal::Image) {
         target = static_cast<QImage *>(painter->paintEngine()->paintDevice());
 
@@ -432,18 +432,18 @@ void QPixmapConvolutionFilter::draw(QPainter *painter, const QPointF &p, const Q
 
         if (mat.type() > QTransform::TxTranslate) {
             // Disabled because of transformation...
-            target = 0;
+            target = nullptr;
         } else {
             QRasterPaintEngine *pe = static_cast<QRasterPaintEngine *>(painter->paintEngine());
             if (pe->clipType() == QRasterPaintEngine::ComplexClip)
                 // disabled because of complex clipping...
-                target = 0;
+                target = nullptr;
             else {
                 QRectF clip = pe->clipBoundingRect();
                 QRectF rect = boundingRectFor(srcRect.isEmpty() ? src.rect() : srcRect);
                 QTransform x = painter->deviceTransform();
                 if (!clip.contains(rect.translated(x.dx() + p.x(), x.dy() + p.y()))) {
-                    target = 0;
+                    target = nullptr;
                 }
 
             }
diff --git a/src/widgets/graphicsview/qgraphicsanchorlayout.cpp b/src/widgets/graphicsview/qgraphicsanchorlayout.cpp
index ea6a8018ca..4f1855a606 100644
--- a/src/widgets/graphicsview/qgraphicsanchorlayout.cpp
+++ b/src/widgets/graphicsview/qgraphicsanchorlayout.cpp
@@ -353,7 +353,7 @@ void QGraphicsAnchorLayout::addAnchors(QGraphicsLayoutItem *firstItem,
     bool ok = true;
     if (orientations & Qt::Horizontal) {
         // Currently, if the first is ok, then the rest of the calls should be ok
-        ok = addAnchor(secondItem, Qt::AnchorLeft, firstItem, Qt::AnchorLeft) != 0;
+        ok = addAnchor(secondItem, Qt::AnchorLeft, firstItem, Qt::AnchorLeft) != nullptr;
         if (ok)
             addAnchor(firstItem, Qt::AnchorRight, secondItem, Qt::AnchorRight);
     }
@@ -465,7 +465,7 @@ void QGraphicsAnchorLayout::removeAt(int index)
     d->removeAnchors(item);
     d->items.remove(index);
 
-    item->setParentLayoutItem(0);
+    item->setParentLayoutItem(nullptr);
     invalidate();
 }
 
diff --git a/src/widgets/graphicsview/qgraphicsanchorlayout_p.cpp b/src/widgets/graphicsview/qgraphicsanchorlayout_p.cpp
index 4f44373cad..af0ee3d38c 100644
--- a/src/widgets/graphicsview/qgraphicsanchorlayout_p.cpp
+++ b/src/widgets/graphicsview/qgraphicsanchorlayout_p.cpp
@@ -61,7 +61,7 @@ QT_BEGIN_NAMESPACE
 const qreal g_offset = (sizeof(qreal) == sizeof(double)) ? QWIDGETSIZE_MAX : QWIDGETSIZE_MAX / 32;
 
 QGraphicsAnchorPrivate::QGraphicsAnchorPrivate(int version)
-    : QObjectPrivate(version), layoutPrivate(0), data(0),
+    : QObjectPrivate(version), layoutPrivate(nullptr), data(nullptr),
       sizePolicy(QSizePolicy::Fixed), preferredSize(0),
       hasSize(true)
 {
@@ -72,7 +72,7 @@ QGraphicsAnchorPrivate::~QGraphicsAnchorPrivate()
     if (data) {
         // The QGraphicsAnchor was already deleted at this moment. We must clean
         // the dangling pointer to avoid double deletion in the AnchorData dtor.
-        data->graphicsAnchor = 0;
+        data->graphicsAnchor = nullptr;
 
         layoutPrivate->removeAnchor(data->from, data->to);
     }
@@ -631,9 +631,9 @@ QGraphicsAnchorLayoutPrivate::QGraphicsAnchorLayoutPrivate()
         spacings[i] = -1;
         graphHasConflicts[i] = false;
 
-        layoutFirstVertex[i] = 0;
-        layoutCentralVertex[i] = 0;
-        layoutLastVertex[i] = 0;
+        layoutFirstVertex[i] = nullptr;
+        layoutCentralVertex[i] = nullptr;
+        layoutLastVertex[i] = nullptr;
     }
 }
 
@@ -981,7 +981,7 @@ bool QGraphicsAnchorLayoutPrivate::simplifyVertices(Orientation orientation)
                 feasible &= replaceVertex(orientation, next, newV, newV->m_secondAnchors);
 
                 // Update the layout vertex information if one of the vertices is a layout vertex.
-                AnchorVertex *layoutVertex = 0;
+                AnchorVertex *layoutVertex = nullptr;
                 if (v->m_item == q)
                     layoutVertex = v;
                 else if (next->m_item == q)
@@ -1035,7 +1035,7 @@ bool QGraphicsAnchorLayoutPrivate::simplifyGraphIteration(QGraphicsAnchorLayoutP
 
     QSet<AnchorVertex *> visited;
     QStack<QPair<AnchorVertex *, AnchorVertex *> > stack;
-    stack.push(qMakePair(static_cast<AnchorVertex *>(0), layoutFirstVertex[orientation]));
+    stack.push(qMakePair(static_cast<AnchorVertex *>(nullptr), layoutFirstVertex[orientation]));
     QVector<AnchorVertex*> candidates;
 
     // Walk depth-first, in the stack we store start of the candidate sequence (beforeSequence)
@@ -1384,7 +1384,7 @@ void QGraphicsAnchorLayoutPrivate::createLayoutEdges()
 
     // Save a reference to layout vertices
     layoutFirstVertex[Horizontal] = internalVertex(layout, Qt::AnchorLeft);
-    layoutCentralVertex[Horizontal] = 0;
+    layoutCentralVertex[Horizontal] = nullptr;
     layoutLastVertex[Horizontal] = internalVertex(layout, Qt::AnchorRight);
 
     // Vertical
@@ -1395,7 +1395,7 @@ void QGraphicsAnchorLayoutPrivate::createLayoutEdges()
 
     // Save a reference to layout vertices
     layoutFirstVertex[Vertical] = internalVertex(layout, Qt::AnchorTop);
-    layoutCentralVertex[Vertical] = 0;
+    layoutCentralVertex[Vertical] = nullptr;
     layoutLastVertex[Vertical] = internalVertex(layout, Qt::AnchorBottom);
 }
 
@@ -1581,7 +1581,7 @@ void QGraphicsAnchorLayoutPrivate::removeCenterAnchors(
     }
 
     if (item == q) {
-        layoutCentralVertex[orientation] = 0;
+        layoutCentralVertex[orientation] = nullptr;
     }
 }
 
@@ -1636,29 +1636,29 @@ QGraphicsAnchor *QGraphicsAnchorLayoutPrivate::addAnchor(QGraphicsLayoutItem *fi
                                                          qreal *spacing)
 {
     Q_Q(QGraphicsAnchorLayout);
-    if ((firstItem == 0) || (secondItem == 0)) {
+    if ((firstItem == nullptr) || (secondItem == nullptr)) {
         qWarning("QGraphicsAnchorLayout::addAnchor(): "
                  "Cannot anchor NULL items");
-        return 0;
+        return nullptr;
     }
 
     if (firstItem == secondItem) {
         qWarning("QGraphicsAnchorLayout::addAnchor(): "
                  "Cannot anchor the item to itself");
-        return 0;
+        return nullptr;
     }
 
     if (edgeOrientation(secondEdge) != edgeOrientation(firstEdge)) {
         qWarning("QGraphicsAnchorLayout::addAnchor(): "
                  "Cannot anchor edges of different orientations");
-        return 0;
+        return nullptr;
     }
 
     const QGraphicsLayoutItem *parentWidget = q->parentLayoutItem();
     if (firstItem == parentWidget || secondItem == parentWidget) {
         qWarning("QGraphicsAnchorLayout::addAnchor(): "
                  "You cannot add the parent of the layout to the layout.");
-        return 0;
+        return nullptr;
     }
 
     // In QGraphicsAnchorLayout, items are represented in its internal
@@ -1770,13 +1770,13 @@ QGraphicsAnchor *QGraphicsAnchorLayoutPrivate::getAnchor(QGraphicsLayoutItem *fi
 {
     // Do not expose internal anchors
     if (firstItem == secondItem)
-        return 0;
+        return nullptr;
 
     const Orientation orientation = edgeOrientation(firstEdge);
     AnchorVertex *v1 = internalVertex(firstItem, firstEdge);
     AnchorVertex *v2 = internalVertex(secondItem, secondEdge);
 
-    QGraphicsAnchor *graphicsAnchor = 0;
+    QGraphicsAnchor *graphicsAnchor = nullptr;
 
     AnchorData *data = graph[orientation].edgeData(v1, v2);
     if (data) {
@@ -1811,7 +1811,7 @@ void QGraphicsAnchorLayoutPrivate::removeAnchor(AnchorVertex *firstVertex,
     removeAnchor_helper(firstVertex, secondVertex);
 
     // Ensure no dangling pointer is left behind
-    firstVertex = secondVertex = 0;
+    firstVertex = secondVertex = nullptr;
 
     // Checking if the item stays in the layout or not
     bool keepFirstItem = false;
@@ -2017,13 +2017,13 @@ QLayoutStyleInfo &QGraphicsAnchorLayoutPrivate::styleInfo() const
     if (styleInfoDirty) {
         Q_Q(const QGraphicsAnchorLayout);
         //### Fix this if QGV ever gets support for Metal style or different Aqua sizes.
-        QWidget *wid = 0;
+        QWidget *wid = nullptr;
 
         QGraphicsLayoutItem *parent = q->parentLayoutItem();
         while (parent && parent->isLayout()) {
             parent = parent->parentLayoutItem();
         }
-        QGraphicsWidget *w = 0;
+        QGraphicsWidget *w = nullptr;
         if (parent) {
             QGraphicsItem *parentItem = parent->graphicsItem();
             if (parentItem && parentItem->isWidget())
@@ -2404,7 +2404,7 @@ QList<QSimplexConstraint *> QGraphicsAnchorLayoutPrivate::constraintsFromSizeHin
     // Look for the layout edge. That can be either the first half in case the
     // layout is split in two, or the whole layout anchor.
     Orientation orient = Orientation(anchors.first()->orientation);
-    AnchorData *layoutEdge = 0;
+    AnchorData *layoutEdge = nullptr;
     if (layoutCentralVertex[orient]) {
         layoutEdge = graph[orient].edgeData(layoutFirstVertex[orient], layoutCentralVertex[orient]);
     } else {
@@ -2423,7 +2423,7 @@ QList<QSimplexConstraint *> QGraphicsAnchorLayoutPrivate::constraintsFromSizeHin
         actualMax = -layoutEdge->minSize;
     }
     if (actualMax != expectedMax) {
-        layoutEdge = 0;
+        layoutEdge = nullptr;
     }
 
     // For each variable, create constraints based on size hints
@@ -2496,8 +2496,8 @@ QGraphicsAnchorLayoutPrivate::getGraphParts(Orientation orientation)
 
     Q_ASSERT(layoutFirstVertex[orientation] && layoutLastVertex[orientation]);
 
-    AnchorData *edgeL1 = 0;
-    AnchorData *edgeL2 = 0;
+    AnchorData *edgeL1 = nullptr;
+    AnchorData *edgeL2 = nullptr;
 
     // The layout may have a single anchor between Left and Right or two half anchors
     // passing through the center
@@ -2625,7 +2625,7 @@ void QGraphicsAnchorLayoutPrivate::setItemsGeometries(const QRectF &geom)
     qreal left;
     qreal right;
 
-    q->getContentsMargins(&left, &top, &right, 0);
+    q->getContentsMargins(&left, &top, &right, nullptr);
     const Qt::LayoutDirection visualDir = visualDirection();
     if (visualDir == Qt::RightToLeft)
         qSwap(left, right);
diff --git a/src/widgets/graphicsview/qgraphicsgridlayout.cpp b/src/widgets/graphicsview/qgraphicsgridlayout.cpp
index 6b7052a0ab..260e1861c7 100644
--- a/src/widgets/graphicsview/qgraphicsgridlayout.cpp
+++ b/src/widgets/graphicsview/qgraphicsgridlayout.cpp
@@ -137,7 +137,7 @@ QGraphicsGridLayout::~QGraphicsGridLayout()
         // ~QGraphicsLayoutItem.
         removeAt(i);
         if (item) {
-            item->setParentLayoutItem(0);
+            item->setParentLayoutItem(nullptr);
             if (item->ownedByLayout())
                 delete item;
         }
@@ -535,11 +535,11 @@ QGraphicsLayoutItem *QGraphicsGridLayout::itemAt(int row, int column) const
     Q_D(const QGraphicsGridLayout);
     if (row < 0 || row >= rowCount() || column < 0 || column >= columnCount()) {
         qWarning("QGraphicsGridLayout::itemAt: invalid row, column %d, %d", row, column);
-        return 0;
+        return nullptr;
     }
     if (QGraphicsGridLayoutEngineItem *engineItem = static_cast<QGraphicsGridLayoutEngineItem*>(d->engine.itemAt(row, column)))
         return engineItem->layoutItem();
-    return 0;
+    return nullptr;
 }
 
 /*!
@@ -583,7 +583,7 @@ void QGraphicsGridLayout::removeAt(int index)
 
     if (QGraphicsGridLayoutEngineItem *gridItem = static_cast<QGraphicsGridLayoutEngineItem*>(d->engine.itemAt(index))) {
         if (QGraphicsLayoutItem *layoutItem = gridItem->layoutItem())
-            layoutItem->setParentLayoutItem(0);
+            layoutItem->setParentLayoutItem(nullptr);
         d->engine.removeItem(gridItem);
 
         // recalculate rowInfo.count if we remove an item that is on the right/bottommost row
diff --git a/src/widgets/graphicsview/qgraphicsitem.cpp b/src/widgets/graphicsview/qgraphicsitem.cpp
index 7c0f836156..6f1eb4b346 100644
--- a/src/widgets/graphicsview/qgraphicsitem.cpp
+++ b/src/widgets/graphicsview/qgraphicsitem.cpp
@@ -1250,7 +1250,7 @@ void QGraphicsItemPrivate::setParentItemHelper(QGraphicsItem *newParent, const Q
 
     if (isWidget)
         static_cast<QGraphicsWidgetPrivate *>(this)->fixFocusChainBeforeReparenting((newParent &&
-                                                        newParent->isWidget()) ? static_cast<QGraphicsWidget *>(newParent) : 0,
+                                                        newParent->isWidget()) ? static_cast<QGraphicsWidget *>(newParent) : nullptr,
                                                         scene);
     if (scene) {
         // Deliver the change to the index
@@ -1293,7 +1293,7 @@ void QGraphicsItemPrivate::setParentItemHelper(QGraphicsItem *newParent, const Q
     // Ensure any last parent focus scope does not point to this item or any of
     // its descendents.
     QGraphicsItem *p = parent;
-    QGraphicsItem *parentFocusScopeItem = 0;
+    QGraphicsItem *parentFocusScopeItem = nullptr;
     while (p) {
         if (p->d_ptr->flags & QGraphicsItem::ItemIsFocusScope) {
             // If this item's focus scope's focus scope item points
@@ -1301,7 +1301,7 @@ void QGraphicsItemPrivate::setParentItemHelper(QGraphicsItem *newParent, const Q
             QGraphicsItem *fsi = p->d_ptr->focusScopeItem;
             if (q_ptr == fsi || q_ptr->isAncestorOf(fsi)) {
                 parentFocusScopeItem = fsi;
-                p->d_ptr->focusScopeItem = 0;
+                p->d_ptr->focusScopeItem = nullptr;
                 fsi->d_ptr->focusScopeItemChange(false);
             }
             break;
@@ -1321,7 +1321,7 @@ void QGraphicsItemPrivate::setParentItemHelper(QGraphicsItem *newParent, const Q
             if (p->d_ptr->flags & QGraphicsItem::ItemIsFocusScope) {
                 if (subFocusItem && subFocusItem != q_ptr) {
                     // Find the subFocusItem's topmost focus scope within the new parent's focusscope
-                    QGraphicsItem *ancestorScope = 0;
+                    QGraphicsItem *ancestorScope = nullptr;
                     QGraphicsItem *p2 = subFocusItem->d_ptr->parent;
                     while (p2 && p2 != p) {
                         if (p2->d_ptr->flags & QGraphicsItem::ItemIsFocusScope)
@@ -1587,7 +1587,7 @@ QGraphicsItem::~QGraphicsItem()
                 if (QAbstractDeclarativeData::destroyed)
                     QAbstractDeclarativeData::destroyed(p->declarativeData, o);
             }
-            p->declarativeData = 0;
+            p->declarativeData = nullptr;
             p->wasDeleted = false;
         }
     }
@@ -1607,14 +1607,14 @@ QGraphicsItem::~QGraphicsItem()
 #endif
 
     clearFocus();
-    setFocusProxy(0);
+    setFocusProxy(nullptr);
 
     // Update focus scope item ptr.
     QGraphicsItem *p = d_ptr->parent;
     while (p) {
         if (p->flags() & ItemIsFocusScope) {
             if (p->d_ptr->focusScopeItem == this)
-                p->d_ptr->focusScopeItem = 0;
+                p->d_ptr->focusScopeItem = nullptr;
             break;
         }
         p = p->d_ptr->parent;
@@ -1630,7 +1630,7 @@ QGraphicsItem::~QGraphicsItem()
         d_ptr->scene->d_func()->removeItemHelper(this);
     } else {
         d_ptr->resetFocusProxy();
-        setParentItem(0);
+        setParentItem(nullptr);
     }
 
 #if QT_CONFIG(graphicseffect)
@@ -1639,7 +1639,7 @@ QGraphicsItem::~QGraphicsItem()
     if (d_ptr->transformData) {
         for(int i = 0; i < d_ptr->transformData->graphicsTransforms.size(); ++i) {
             QGraphicsTransform *t = d_ptr->transformData->graphicsTransforms.at(i);
-            static_cast<QGraphicsTransformPrivate *>(t->d_ptr.data())->item = 0;
+            static_cast<QGraphicsTransformPrivate *>(t->d_ptr.data())->item = nullptr;
             delete t;
         }
     }
@@ -1751,7 +1751,7 @@ QGraphicsWidget *QGraphicsItem::parentWidget() const
     QGraphicsItem *p = parentItem();
     while (p && !p->isWidget())
         p = p->parentItem();
-    return (p && p->isWidget()) ? static_cast<QGraphicsWidget *>(p) : 0;
+    return (p && p->isWidget()) ? static_cast<QGraphicsWidget *>(p) : nullptr;
 }
 
 /*!
@@ -1811,7 +1811,7 @@ QGraphicsItem *QGraphicsItem::panel() const
 */
 QGraphicsObject *QGraphicsItem::toGraphicsObject()
 {
-    return d_ptr->isObject ? static_cast<QGraphicsObject *>(this) : 0;
+    return d_ptr->isObject ? static_cast<QGraphicsObject *>(this) : nullptr;
 }
 
 /*!
@@ -1822,7 +1822,7 @@ QGraphicsObject *QGraphicsItem::toGraphicsObject()
 */
 const QGraphicsObject *QGraphicsItem::toGraphicsObject() const
 {
-    return d_ptr->isObject ? static_cast<const QGraphicsObject *>(this) : 0;
+    return d_ptr->isObject ? static_cast<const QGraphicsObject *>(this) : nullptr;
 }
 
 /*!
@@ -2224,7 +2224,7 @@ bool QGraphicsItem::isBlockedByModalPanel(QGraphicsItem **blockingPanel) const
         return false;
 
 
-    QGraphicsItem *dummy = 0;
+    QGraphicsItem *dummy = nullptr;
     if (!blockingPanel)
         blockingPanel = &dummy;
 
@@ -2420,7 +2420,7 @@ bool QGraphicsItem::isVisibleTo(const QGraphicsItem *parent) const
         if (p->d_ptr->explicitlyHidden)
             return false;
     } while ((p = p->d_ptr->parent));
-    return parent == 0;
+    return parent == nullptr;
 }
 
 /*!
@@ -2959,7 +2959,7 @@ void QGraphicsItem::setGraphicsEffect(QGraphicsEffect *effect)
 
     if (d_ptr->graphicsEffect) {
         delete d_ptr->graphicsEffect;
-        d_ptr->graphicsEffect = 0;
+        d_ptr->graphicsEffect = nullptr;
     } else if (d_ptr->parent) {
         d_ptr->parent->d_ptr->updateChildWithGraphicsEffectFlagRecursively();
     }
@@ -2984,7 +2984,7 @@ void QGraphicsItemPrivate::updateChildWithGraphicsEffectFlagRecursively()
         if (itemPrivate->mayHaveChildWithGraphicsEffect)
             return;
         itemPrivate->mayHaveChildWithGraphicsEffect = 1;
-    } while ((itemPrivate = itemPrivate->parent ? itemPrivate->parent->d_ptr.data() : 0));
+    } while ((itemPrivate = itemPrivate->parent ? itemPrivate->parent->d_ptr.data() : nullptr));
 #endif
 }
 
@@ -3396,13 +3396,13 @@ void QGraphicsItem::setActive(bool active)
             if (!activePanel || activePanel == thisPanel) {
                 // Deactivate this item, and reactivate the parent panel,
                 // or the last active panel (if any).
-                QGraphicsItem *nextToActivate = 0;
+                QGraphicsItem *nextToActivate = nullptr;
                 if (d_ptr->parent)
                     nextToActivate = d_ptr->parent->panel();
                 if (!nextToActivate)
                     nextToActivate = d_ptr->scene->d_func()->lastActivePanel;
                 if (nextToActivate == this || isAncestorOf(nextToActivate))
-                    nextToActivate = 0;
+                    nextToActivate = nullptr;
                 d_ptr->scene->setActivePanel(nextToActivate);
             }
         }
@@ -3499,7 +3499,7 @@ void QGraphicsItemPrivate::setFocusHelper(Qt::FocusReason focusReason, bool clim
     }
 
     // Update the child focus chain.
-    QGraphicsItem *commonAncestor = 0;
+    QGraphicsItem *commonAncestor = nullptr;
     if (scene && scene->focusItem() && scene->focusItem()->panel() == q_ptr->panel()) {
         commonAncestor = scene->focusItem()->commonAncestorItem(f);
         scene->focusItem()->d_ptr->clearSubFocus(scene->focusItem(), commonAncestor);
@@ -3552,7 +3552,7 @@ void QGraphicsItemPrivate::clearFocusHelper(bool giveFocusToParent, bool hiddenB
             while (p) {
                 if (p->flags() & QGraphicsItem::ItemIsFocusScope) {
                     if (p->d_ptr->focusScopeItem == q_ptr) {
-                        p->d_ptr->focusScopeItem = 0;
+                        p->d_ptr->focusScopeItem = nullptr;
                         if (!subFocusItem->hasFocus()) //if it has focus, focusScopeItemChange is called elsewhere
                             focusScopeItemChange(false);
                     }
@@ -3572,7 +3572,7 @@ void QGraphicsItemPrivate::clearFocusHelper(bool giveFocusToParent, bool hiddenB
             clearSubFocus(q_ptr);
 
         // If this item has the scene's input focus, clear it.
-        scene->setFocusItem(0);
+        scene->setFocusItem(nullptr);
     }
 }
 
@@ -3621,7 +3621,7 @@ void QGraphicsItem::setFocusProxy(QGraphicsItem *item)
             qWarning("QGraphicsItem::setFocusProxy: focus proxy must be in same scene");
             return;
         }
-        for (QGraphicsItem *f = item->focusProxy(); f != 0; f = f->focusProxy()) {
+        for (QGraphicsItem *f = item->focusProxy(); f != nullptr; f = f->focusProxy()) {
             if (f == this) {
                 qWarning("QGraphicsItem::setFocusProxy: %p is already in the focus proxy chain", item);
                 return;
@@ -4452,7 +4452,7 @@ QTransform QGraphicsItem::deviceTransform(const QTransform &viewportTransform) c
 QTransform QGraphicsItem::itemTransform(const QGraphicsItem *other, bool *ok) const
 {
     // Catch simple cases first.
-    if (other == 0) {
+    if (other == nullptr) {
         qWarning("QGraphicsItem::itemTransform: null pointer passed");
         return QTransform();
     }
@@ -4892,7 +4892,7 @@ void QGraphicsItem::stackBefore(const QGraphicsItem *sibling)
     }
     QList<QGraphicsItem *> *siblings = d_ptr->parent
                                        ? &d_ptr->parent->d_ptr->children
-                                       : (d_ptr->scene ? &d_ptr->scene->d_func()->topLevelItems : 0);
+                                       : (d_ptr->scene ? &d_ptr->scene->d_func()->topLevelItems : nullptr);
     if (!siblings) {
         qWarning("QGraphicsItem::stackUnder: cannot stack under %p, which must be a sibling", sibling);
         return;
@@ -4949,7 +4949,7 @@ QRectF QGraphicsItem::childrenBoundingRect() const
         return d_ptr->childrenBoundingRect;
 
     d_ptr->childrenBoundingRect = QRectF();
-    d_ptr->childrenBoundingRectHelper(0, &d_ptr->childrenBoundingRect, 0);
+    d_ptr->childrenBoundingRectHelper(nullptr, &d_ptr->childrenBoundingRect, nullptr);
     d_ptr->dirtyChildrenBoundingRect = 0;
     return d_ptr->childrenBoundingRect;
 }
@@ -5422,7 +5422,7 @@ QRegion QGraphicsItem::boundingRegion(const QTransform &itemToDeviceTransform) c
 
     // Render
     QStyleOptionGraphicsItem option;
-    const_cast<QGraphicsItem *>(this)->paint(&p, &option, 0);
+    const_cast<QGraphicsItem *>(this)->paint(&p, &option, nullptr);
     p.end();
 
     // Transform QRegion back to device space
@@ -5575,7 +5575,7 @@ void QGraphicsItemPrivate::invalidateParentGraphicsEffectsRecursively()
             if (!itemPrivate->updateDueToGraphicsEffect)
                 static_cast<QGraphicsItemEffectSourcePrivate *>(itemPrivate->graphicsEffect->d_func()->source->d_func())->invalidateCache();
         }
-    } while ((itemPrivate = itemPrivate->parent ? itemPrivate->parent->d_ptr.data() : 0));
+    } while ((itemPrivate = itemPrivate->parent ? itemPrivate->parent->d_ptr.data() : nullptr));
 }
 
 void QGraphicsItemPrivate::invalidateChildGraphicsEffectsRecursively(QGraphicsItemPrivate::InvalidateReason reason)
@@ -5739,7 +5739,7 @@ void QGraphicsItemPrivate::ensureSceneTransformRecursive(QGraphicsItem **topMost
     if (*topMostDirtyItem == q_ptr) {
         if (!dirtySceneTransform)
             return; // OK, neither my ancestors nor I have dirty scene transforms.
-        *topMostDirtyItem = 0;
+        *topMostDirtyItem = nullptr;
     } else if (*topMostDirtyItem) {
         return; // Continue backtrack.
     }
@@ -5771,7 +5771,7 @@ void QGraphicsItemPrivate::setSubFocus(QGraphicsItem *rootItem, QGraphicsItem *s
         if (parent != q_ptr && parent->d_ptr->subFocusItem) {
             if (parent->d_ptr->subFocusItem == q_ptr)
                 break;
-            parent->d_ptr->subFocusItem->d_ptr->clearSubFocus(0, stopItem);
+            parent->d_ptr->subFocusItem->d_ptr->clearSubFocus(nullptr, stopItem);
         }
         parent->d_ptr->subFocusItem = q_ptr;
         parent->d_ptr->subFocusItemChange();
@@ -5793,7 +5793,7 @@ void QGraphicsItemPrivate::clearSubFocus(QGraphicsItem *rootItem, QGraphicsItem
     do {
         if (parent->d_ptr->subFocusItem != q_ptr)
             break;
-        parent->d_ptr->subFocusItem = 0;
+        parent->d_ptr->subFocusItem = nullptr;
         if (parent != stopItem && !parent->isAncestorOf(stopItem))
             parent->d_ptr->subFocusItemChange();
     } while (!parent->isPanel() && (parent = parent->d_ptr->parent));
@@ -5808,7 +5808,7 @@ void QGraphicsItemPrivate::clearSubFocus(QGraphicsItem *rootItem, QGraphicsItem
 void QGraphicsItemPrivate::resetFocusProxy()
 {
     for (int i = 0; i < focusProxyRefs.size(); ++i)
-        *focusProxyRefs.at(i) = 0;
+        *focusProxyRefs.at(i) = nullptr;
     focusProxyRefs.clear();
 }
 
@@ -7322,7 +7322,7 @@ void QGraphicsItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
         }
 
         // Find the active view.
-        QGraphicsView *view = 0;
+        QGraphicsView *view = nullptr;
         if (event->widget())
             view = qobject_cast<QGraphicsView *>(event->widget()->parentWidget());
 
@@ -7330,7 +7330,7 @@ void QGraphicsItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
         int i = 0;
         bool movedMe = false;
         while (i <= selectedItems.size()) {
-            QGraphicsItem *item = 0;
+            QGraphicsItem *item = nullptr;
             if (i < selectedItems.size())
                 item = selectedItems.at(i);
             else
@@ -7891,7 +7891,7 @@ void QGraphicsItemPrivate::children_append(QDeclarativeListProperty<QGraphicsObj
         if (QGraphicsItemPrivate::get(graphicsObject)->sendParentChangeNotification) {
             item->setParentItem(graphicsObject);
         } else {
-            QGraphicsItemPrivate::get(item)->setParentItemHelper(graphicsObject, 0, 0);
+            QGraphicsItemPrivate::get(item)->setParentItemHelper(graphicsObject, nullptr, nullptr);
         }
     }
 }
@@ -7908,7 +7908,7 @@ QGraphicsObject *QGraphicsItemPrivate::children_at(QDeclarativeListProperty<QGra
     if (index >= 0 && index < d->children.count())
         return d->children.at(index)->toGraphicsObject();
     else
-        return 0;
+        return nullptr;
 }
 
 void QGraphicsItemPrivate::children_clear(QDeclarativeListProperty<QGraphicsObject> *list)
@@ -7917,10 +7917,10 @@ void QGraphicsItemPrivate::children_clear(QDeclarativeListProperty<QGraphicsObje
     int childCount = d->children.count();
     if (d->sendParentChangeNotification) {
         for (int index = 0; index < childCount; index++)
-            d->children.at(0)->setParentItem(0);
+            d->children.at(0)->setParentItem(nullptr);
     } else {
         for (int index = 0; index < childCount; index++)
-            QGraphicsItemPrivate::get(d->children.at(0))->setParentItemHelper(0, 0, 0);
+            QGraphicsItemPrivate::get(d->children.at(0))->setParentItemHelper(nullptr, nullptr, nullptr);
     }
 }
 
@@ -9949,7 +9949,7 @@ class QGraphicsTextItemPrivate
 {
 public:
     QGraphicsTextItemPrivate()
-        : control(0), pageNumber(0), useDefaultImpl(false), tabChangesFocus(false), clickCausedFocus(0)
+        : control(nullptr), pageNumber(0), useDefaultImpl(false), tabChangesFocus(false), clickCausedFocus(0)
     { }
 
     mutable QWidgetTextControl *control;
@@ -11232,7 +11232,7 @@ void QGraphicsItemGroup::removeFromGroup(QGraphicsItem *item)
     // ### Expensive, we could maybe use dirtySceneTransform bit for optimization
 
     item->setTransform(itemTransform);
-    item->d_func()->setIsMemberOfGroup(item->group() != 0);
+    item->d_func()->setIsMemberOfGroup(item->group() != nullptr);
 
     // ### Quite expensive. But removeFromGroup() isn't called very often.
     prepareGeometryChange();
@@ -11412,18 +11412,18 @@ QPixmap QGraphicsItemEffectSourcePrivate::pixmap(Qt::CoordinateSystem system, QP
         QTransform sceneTransform = item->sceneTransform();
         QTransform newEffectTransform = sceneTransform.inverted();
         newEffectTransform *= effectTransform;
-        scened->draw(item, &pixmapPainter, 0, &sceneTransform, 0, 0, qreal(1.0),
+        scened->draw(item, &pixmapPainter, nullptr, &sceneTransform, nullptr, nullptr, qreal(1.0),
                      &newEffectTransform, false, true);
     } else if (deviceCoordinates) {
         // Device coordinates with info.
-        scened->draw(item, &pixmapPainter, info->viewTransform, info->transformPtr, 0,
+        scened->draw(item, &pixmapPainter, info->viewTransform, info->transformPtr, nullptr,
                      info->widget, info->opacity, &effectTransform, info->wasDirtySceneTransform,
                      info->drawItem);
     } else {
         // Item coordinates with info.
         QTransform newEffectTransform = info->transformPtr->inverted();
         newEffectTransform *= effectTransform;
-        scened->draw(item, &pixmapPainter, info->viewTransform, info->transformPtr, 0,
+        scened->draw(item, &pixmapPainter, info->viewTransform, info->transformPtr, nullptr,
                      info->widget, info->opacity, &newEffectTransform, info->wasDirtySceneTransform,
                      info->drawItem);
     }
diff --git a/src/widgets/graphicsview/qgraphicsitemanimation.cpp b/src/widgets/graphicsview/qgraphicsitemanimation.cpp
index ad77e2f260..1c5dbf265c 100644
--- a/src/widgets/graphicsview/qgraphicsitemanimation.cpp
+++ b/src/widgets/graphicsview/qgraphicsitemanimation.cpp
@@ -106,7 +106,7 @@ class QGraphicsItemAnimationPrivate
 {
 public:
     inline QGraphicsItemAnimationPrivate()
-        : q(0), timeLine(0), item(0), step(0)
+        : q(nullptr), timeLine(nullptr), item(nullptr), step(0)
     { }
 
     QGraphicsItemAnimation *q;
diff --git a/src/widgets/graphicsview/qgraphicslayout_p.cpp b/src/widgets/graphicsview/qgraphicslayout_p.cpp
index 59ed7acd72..c10763d065 100644
--- a/src/widgets/graphicsview/qgraphicslayout_p.cpp
+++ b/src/widgets/graphicsview/qgraphicslayout_p.cpp
@@ -97,7 +97,7 @@ void QGraphicsLayoutPrivate::getMargin(qreal *result, qreal userMargin, QStyle::
         *result = 0.0;
         if (QGraphicsItem *layoutParentItem = parentItem()) {
             if (layoutParentItem->isWidget())
-                *result = (qreal)static_cast<QGraphicsWidget*>(layoutParentItem)->style()->pixelMetric(pm, 0);
+                *result = (qreal)static_cast<QGraphicsWidget*>(layoutParentItem)->style()->pixelMetric(pm, nullptr);
         }
     }
 }
diff --git a/src/widgets/graphicsview/qgraphicslayoutitem.cpp b/src/widgets/graphicsview/qgraphicslayoutitem.cpp
index 1192bad51e..8694dcb36b 100644
--- a/src/widgets/graphicsview/qgraphicslayoutitem.cpp
+++ b/src/widgets/graphicsview/qgraphicslayoutitem.cpp
@@ -105,7 +105,7 @@ static void normalizeHints(qreal &minimum, qreal &preferred, qreal &maximum, qre
     \internal
 */
 QGraphicsLayoutItemPrivate::QGraphicsLayoutItemPrivate(QGraphicsLayoutItem *par, bool layout)
-    : parent(par), userSizeHints(0), isLayout(layout), ownedByLayout(false), graphicsItem(0)
+    : parent(par), userSizeHints(nullptr), isLayout(layout), ownedByLayout(false), graphicsItem(nullptr)
 {
 }
 
diff --git a/src/widgets/graphicsview/qgraphicslayoutstyleinfo.cpp b/src/widgets/graphicsview/qgraphicslayoutstyleinfo.cpp
index da2510a8cb..2f1526cc78 100644
--- a/src/widgets/graphicsview/qgraphicslayoutstyleinfo.cpp
+++ b/src/widgets/graphicsview/qgraphicslayoutstyleinfo.cpp
@@ -48,7 +48,7 @@
 QT_BEGIN_NAMESPACE
 
 QGraphicsLayoutStyleInfo::QGraphicsLayoutStyleInfo(const QGraphicsLayoutPrivate *layout)
-    : m_layout(layout), m_style(0)
+    : m_layout(layout), m_style(nullptr)
 {
     m_widget.reset(new QWidget); // pixelMetric might need a widget ptr
     m_styleOption.initFrom(m_widget.get());
diff --git a/src/widgets/graphicsview/qgraphicslinearlayout.cpp b/src/widgets/graphicsview/qgraphicslinearlayout.cpp
index 22633df4e3..f76cc61586 100644
--- a/src/widgets/graphicsview/qgraphicslinearlayout.cpp
+++ b/src/widgets/graphicsview/qgraphicslinearlayout.cpp
@@ -211,7 +211,7 @@ QGraphicsLinearLayout::~QGraphicsLinearLayout()
         // ~QGraphicsLayoutItem.
         removeAt(i);
         if (item) {
-            item->setParentLayoutItem(0);
+            item->setParentLayoutItem(nullptr);
             if (item->ownedByLayout())
                 delete item;
         }
@@ -310,7 +310,7 @@ void QGraphicsLinearLayout::removeItem(QGraphicsLayoutItem *item)
 {
     Q_D(QGraphicsLinearLayout);
     if (QGraphicsGridLayoutEngineItem *gridItem = d->engine.findLayoutItem(item)) {
-        item->setParentLayoutItem(0);
+        item->setParentLayoutItem(nullptr);
         d->removeGridItem(gridItem);
         delete gridItem;
         invalidate();
@@ -333,7 +333,7 @@ void QGraphicsLinearLayout::removeAt(int index)
 
     if (QGraphicsGridLayoutEngineItem *gridItem = static_cast<QGraphicsGridLayoutEngineItem*>(d->engine.itemAt(index))) {
         if (QGraphicsLayoutItem *layoutItem = gridItem->layoutItem())
-            layoutItem->setParentLayoutItem(0);
+            layoutItem->setParentLayoutItem(nullptr);
         d->removeGridItem(gridItem);
         delete gridItem;
         invalidate();
@@ -483,9 +483,9 @@ QGraphicsLayoutItem *QGraphicsLinearLayout::itemAt(int index) const
     Q_D(const QGraphicsLinearLayout);
     if (index < 0 || index >= d->engine.itemCount()) {
         qWarning("QGraphicsLinearLayout::itemAt: invalid index %d", index);
-        return 0;
+        return nullptr;
     }
-    QGraphicsLayoutItem *item = 0;
+    QGraphicsLayoutItem *item = nullptr;
     if (QGraphicsGridLayoutEngineItem *gridItem = static_cast<QGraphicsGridLayoutEngineItem *>(d->engine.itemAt(index)))
         item = gridItem->layoutItem();
     return item;
diff --git a/src/widgets/graphicsview/qgraphicsproxywidget.cpp b/src/widgets/graphicsview/qgraphicsproxywidget.cpp
index c60dca7a90..4d4958c674 100644
--- a/src/widgets/graphicsview/qgraphicsproxywidget.cpp
+++ b/src/widgets/graphicsview/qgraphicsproxywidget.cpp
@@ -291,7 +291,7 @@ void QGraphicsProxyWidgetPrivate::sendWidgetMouseEvent(QGraphicsSceneMouseEvent
     }
 
     if (!lastWidgetUnderMouse) {
-        QApplicationPrivate::dispatchEnterLeave(embeddedMouseGrabber ? embeddedMouseGrabber : receiver, 0, event->screenPos());
+        QApplicationPrivate::dispatchEnterLeave(embeddedMouseGrabber ? embeddedMouseGrabber : receiver, nullptr, event->screenPos());
         lastWidgetUnderMouse = receiver;
     }
 
@@ -315,10 +315,10 @@ void QGraphicsProxyWidgetPrivate::sendWidgetMouseEvent(QGraphicsSceneMouseEvent
         if (q->rect().contains(event->pos()) && q->acceptHoverEvents())
             lastWidgetUnderMouse = alienWidget ? alienWidget : widget;
         else // released on the frame our outside the item, or doesn't accept hover events.
-            lastWidgetUnderMouse = 0;
+            lastWidgetUnderMouse = nullptr;
 
         QApplicationPrivate::dispatchEnterLeave(lastWidgetUnderMouse, embeddedMouseGrabber, event->screenPos());
-        embeddedMouseGrabber = 0;
+        embeddedMouseGrabber = nullptr;
 
 #ifndef QT_NO_CURSOR
         // ### Restore the cursor, don't override it.
@@ -368,7 +368,7 @@ void QGraphicsProxyWidgetPrivate::removeSubFocusHelper(QWidget *widget, Qt::Focu
 QWidget *QGraphicsProxyWidgetPrivate::findFocusChild(QWidget *child, bool next) const
 {
     if (!widget)
-        return 0;
+        return nullptr;
 
     // Run around the focus chain until we find a widget that can take tab focus.
     if (!child) {
@@ -376,12 +376,12 @@ QWidget *QGraphicsProxyWidgetPrivate::findFocusChild(QWidget *child, bool next)
     } else {
         child = next ? child->d_func()->focus_next : child->d_func()->focus_prev;
         if ((next && child == widget) || (!next && child == widget->d_func()->focus_prev)) {
-             return 0;
+             return nullptr;
         }
     }
 
     if (!child)
-        return 0;
+        return nullptr;
 
     QWidget *oldChild = child;
     uint focus_flag = qt_tab_all_widgets() ? Qt::TabFocus : Qt::StrongFocus;
@@ -394,7 +394,7 @@ QWidget *QGraphicsProxyWidgetPrivate::findFocusChild(QWidget *child, bool next)
         }
         child = next ? child->d_func()->focus_next : child->d_func()->focus_prev;
     } while (child != oldChild && !(next && child == widget) && !(!next && child == widget->d_func()->focus_prev));
-    return 0;
+    return nullptr;
 }
 
 /*!
@@ -405,9 +405,9 @@ void QGraphicsProxyWidgetPrivate::_q_removeWidgetSlot()
     Q_Q(QGraphicsProxyWidget);
     if (!widget.isNull()) {
         if (const auto &extra = widget->d_func()->extra)
-            extra->proxyWidget = 0;
+            extra->proxyWidget = nullptr;
     }
-    widget = 0;
+    widget = nullptr;
     delete q;
 }
 
@@ -430,7 +430,7 @@ void QGraphicsProxyWidgetPrivate::updateProxyGeometryFromWidget()
     QRectF widgetGeometry = widget->geometry();
     QWidget *parentWidget = widget->parentWidget();
     if (widget->isWindow()) {
-        QGraphicsProxyWidget *proxyParent = 0;
+        QGraphicsProxyWidget *proxyParent = nullptr;
         if (parentWidget && (proxyParent = qobject_cast<QGraphicsProxyWidget *>(q->parentWidget()))) {
             // Nested window proxy (e.g., combobox popup), map widget to the
             // parent widget's global coordinates, and map that to the parent
@@ -497,7 +497,7 @@ void QGraphicsProxyWidgetPrivate::unembedSubWindow(QWidget *subWin)
         if (child->isWidget()) {
             if (QGraphicsProxyWidget *proxy = qobject_cast<QGraphicsProxyWidget *>(static_cast<QGraphicsWidget *>(child))) {
                 if (proxy->widget() == subWin) {
-                    proxy->setWidget(0);
+                    proxy->setWidget(nullptr);
                     scene->removeItem(proxy);
                     delete proxy;
                     return;
@@ -598,7 +598,7 @@ void QGraphicsProxyWidgetPrivate::setWidget_helper(QWidget *newWidget, bool auto
         QObject::disconnect(widget, SIGNAL(destroyed()), q, SLOT(_q_removeWidgetSlot()));
         widget->removeEventFilter(q);
         widget->setAttribute(Qt::WA_DontShowOnScreen, false);
-        widget->d_func()->extra->proxyWidget = 0;
+        widget->d_func()->extra->proxyWidget = nullptr;
         resolveFont(inheritedFontResolveMask);
         resolvePalette(inheritedPaletteResolveMask);
         widget->update();
@@ -1081,7 +1081,7 @@ void QGraphicsProxyWidget::dragLeaveEvent(QGraphicsSceneDragDropEvent *event)
         return;
     QDragLeaveEvent proxyDragLeave;
     QCoreApplication::sendEvent(d->dragDropWidget, &proxyDragLeave);
-    d->dragDropWidget = 0;
+    d->dragDropWidget = nullptr;
 #endif
 }
 
@@ -1143,7 +1143,7 @@ void QGraphicsProxyWidget::dragMoveEvent(QGraphicsSceneDragDropEvent *event)
             // Leave the last drag drop item
             QDragLeaveEvent dragLeave;
             QCoreApplication::sendEvent(d->dragDropWidget, &dragLeave);
-            d->dragDropWidget = 0;
+            d->dragDropWidget = nullptr;
         }
         // Propagate
         event->setDropAction(Qt::IgnoreAction);
@@ -1165,7 +1165,7 @@ void QGraphicsProxyWidget::dropEvent(QGraphicsSceneDragDropEvent *event)
         QDropEvent dropEvent(widgetPos, event->possibleActions(), event->mimeData(), event->buttons(), event->modifiers());
         QCoreApplication::sendEvent(d->dragDropWidget, &dropEvent);
         event->setAccepted(dropEvent.isAccepted());
-        d->dragDropWidget = 0;
+        d->dragDropWidget = nullptr;
     }
 #endif
 }
@@ -1188,8 +1188,8 @@ void QGraphicsProxyWidget::hoverLeaveEvent(QGraphicsSceneHoverEvent *event)
     Q_D(QGraphicsProxyWidget);
     // If hoverMove was compressed away, make sure we update properly here.
     if (d->lastWidgetUnderMouse) {
-        QApplicationPrivate::dispatchEnterLeave(0, d->lastWidgetUnderMouse, event->screenPos());
-        d->lastWidgetUnderMouse = 0;
+        QApplicationPrivate::dispatchEnterLeave(nullptr, d->lastWidgetUnderMouse, event->screenPos());
+        d->lastWidgetUnderMouse = nullptr;
     }
 }
 
@@ -1205,13 +1205,13 @@ void QGraphicsProxyWidget::hoverMoveEvent(QGraphicsSceneHoverEvent *event)
     // Ignore events on the window frame.
     if (!d->widget || !rect().contains(event->pos())) {
         if (d->lastWidgetUnderMouse) {
-            QApplicationPrivate::dispatchEnterLeave(0, d->lastWidgetUnderMouse, event->screenPos());
-            d->lastWidgetUnderMouse = 0;
+            QApplicationPrivate::dispatchEnterLeave(nullptr, d->lastWidgetUnderMouse, event->screenPos());
+            d->lastWidgetUnderMouse = nullptr;
         }
         return;
     }
 
-    d->embeddedMouseGrabber = 0;
+    d->embeddedMouseGrabber = nullptr;
     d->sendWidgetMouseEvent(event);
 }
 
@@ -1230,7 +1230,7 @@ void QGraphicsProxyWidget::ungrabMouseEvent(QEvent *event)
 {
     Q_D(QGraphicsProxyWidget);
     Q_UNUSED(event);
-    d->embeddedMouseGrabber = 0;
+    d->embeddedMouseGrabber = nullptr;
 }
 
 /*!
@@ -1372,12 +1372,12 @@ void QGraphicsProxyWidget::focusInEvent(QFocusEvent *event)
 
     switch (event->reason()) {
     case Qt::TabFocusReason: {
-        if (QWidget *focusChild = d->findFocusChild(0, true))
+        if (QWidget *focusChild = d->findFocusChild(nullptr, true))
             focusChild->setFocus(event->reason());
         break;
     }
     case Qt::BacktabFocusReason:
-        if (QWidget *focusChild = d->findFocusChild(0, false))
+        if (QWidget *focusChild = d->findFocusChild(nullptr, false))
             focusChild->setFocus(event->reason());
         break;
     default:
@@ -1578,16 +1578,16 @@ QGraphicsProxyWidget *QGraphicsProxyWidget::createProxyForChildWidget(QWidget *c
         return proxy;
     if (!child->parentWidget()) {
         qWarning("QGraphicsProxyWidget::createProxyForChildWidget: top-level widget not in a QGraphicsScene");
-        return 0;
+        return nullptr;
     }
 
     QGraphicsProxyWidget *parentProxy = createProxyForChildWidget(child->parentWidget());
     if (!parentProxy)
-        return 0;
+        return nullptr;
 
     if (!QMetaObject::invokeMethod(parentProxy, "newProxyWidget",  Qt::DirectConnection,
          Q_RETURN_ARG(QGraphicsProxyWidget*, proxy), Q_ARG(const QWidget*, child)))
-        return 0;
+        return nullptr;
     proxy->setParent(parentProxy);
     proxy->setWidget(child);
     return proxy;
diff --git a/src/widgets/graphicsview/qgraphicsscene.cpp b/src/widgets/graphicsview/qgraphicsscene.cpp
index d641d17232..1c6e68def1 100644
--- a/src/widgets/graphicsview/qgraphicsscene.cpp
+++ b/src/widgets/graphicsview/qgraphicsscene.cpp
@@ -278,7 +278,7 @@ static void _q_hoverFromMouseEvent(QGraphicsSceneHoverEvent *hover, const QGraph
 */
 QGraphicsScenePrivate::QGraphicsScenePrivate()
     : indexMethod(QGraphicsScene::BspTreeIndex),
-      index(0),
+      index(nullptr),
       lastItemCount(0),
       hasSceneRect(false),
       dirtyGrowingItemsBoundingRect(true),
@@ -301,19 +301,19 @@ QGraphicsScenePrivate::QGraphicsScenePrivate()
       minimumRenderSize(0.0),
       selectionChanging(0),
       rectAdjust(2),
-      focusItem(0),
-      lastFocusItem(0),
-      passiveFocusItem(0),
-      tabFocusFirst(0),
-      activePanel(0),
-      lastActivePanel(0),
+      focusItem(nullptr),
+      lastFocusItem(nullptr),
+      passiveFocusItem(nullptr),
+      tabFocusFirst(nullptr),
+      activePanel(nullptr),
+      lastActivePanel(nullptr),
       activationRefCount(0),
       childExplicitActivation(0),
-      lastMouseGrabberItem(0),
-      dragDropItem(0),
-      enterWidget(0),
+      lastMouseGrabberItem(nullptr),
+      dragDropItem(nullptr),
+      enterWidget(nullptr),
       lastDropAction(Qt::IgnoreAction),
-      style(0)
+      style(nullptr)
 {
 }
 
@@ -443,8 +443,8 @@ void QGraphicsScenePrivate::_q_polishItems()
         return;
 
     const QVariant booleanTrueVariant(true);
-    QGraphicsItem *item = 0;
-    QGraphicsItemPrivate *itemd = 0;
+    QGraphicsItem *item = nullptr;
+    QGraphicsItemPrivate *itemd = nullptr;
     const int oldUnpolishedCount = unpolishedItems.count();
 
     for (int i = 0; i < oldUnpolishedCount; ++i) {
@@ -602,7 +602,7 @@ void QGraphicsScenePrivate::removeItemHelper(QGraphicsItem *item)
         unregisterScenePosItem(item);
 
     QGraphicsScene *oldScene = item->d_func()->scene;
-    item->d_func()->scene = 0;
+    item->d_func()->scene = nullptr;
 
     //We need to remove all children first because they might use their parent
     //attributes (e.g. sceneTransform).
@@ -614,7 +614,7 @@ void QGraphicsScenePrivate::removeItemHelper(QGraphicsItem *item)
 
     if (!item->d_ptr->inDestructor && !item->parentItem() && item->isWidget()) {
         QGraphicsWidget *widget = static_cast<QGraphicsWidget *>(item);
-        widget->d_func()->fixFocusChainBeforeReparenting(0, oldScene, 0);
+        widget->d_func()->fixFocusChainBeforeReparenting(nullptr, oldScene, nullptr);
     }
 
     // Unregister focus proxy.
@@ -625,7 +625,7 @@ void QGraphicsScenePrivate::removeItemHelper(QGraphicsItem *item)
         if (parentItem->scene()) {
             Q_ASSERT_X(parentItem->scene() == q, "QGraphicsScene::removeItem",
                        "Parent item's scene is different from this item's scene");
-            item->setParentItem(0);
+            item->setParentItem(nullptr);
         }
     } else {
         unregisterTopLevelItem(item);
@@ -633,17 +633,17 @@ void QGraphicsScenePrivate::removeItemHelper(QGraphicsItem *item)
 
     // Reset the mouse grabber and focus item data.
     if (item == focusItem)
-        focusItem = 0;
+        focusItem = nullptr;
     if (item == lastFocusItem)
-        lastFocusItem = 0;
+        lastFocusItem = nullptr;
     if (item == passiveFocusItem)
-        passiveFocusItem = 0;
+        passiveFocusItem = nullptr;
     if (item == activePanel) {
         // ### deactivate...
-        activePanel = 0;
+        activePanel = nullptr;
     }
     if (item == lastActivePanel)
-        lastActivePanel = 0;
+        lastActivePanel = nullptr;
 
     // Change tabFocusFirst to the next widget in focus chain if removing the current one.
     if (item == tabFocusFirst) {
@@ -651,7 +651,7 @@ void QGraphicsScenePrivate::removeItemHelper(QGraphicsItem *item)
         if (wd->focusNext && wd->focusNext != tabFocusFirst && wd->focusNext->scene() == q)
             tabFocusFirst = wd->focusNext;
         else
-            tabFocusFirst = 0;
+            tabFocusFirst = nullptr;
     }
 
     // Cancel active touches
@@ -705,11 +705,11 @@ void QGraphicsScenePrivate::removeItemHelper(QGraphicsItem *item)
 
     // Reset the last mouse grabber item
     if (item == lastMouseGrabberItem)
-        lastMouseGrabberItem = 0;
+        lastMouseGrabberItem = nullptr;
 
     // Reset the current drop item
     if (item == dragDropItem)
-        dragDropItem = 0;
+        dragDropItem = nullptr;
 
     // Reenable selectionChanged() for individual items
     --selectionChanging;
@@ -752,8 +752,8 @@ void QGraphicsScenePrivate::setActivePanelHelper(QGraphicsItem *item, bool durin
     q->setFocus(Qt::ActiveWindowFocusReason);
 
     // Find the item's panel.
-    QGraphicsItem *panel = item ? item->panel() : 0;
-    lastActivePanel = panel ? activePanel : 0;
+    QGraphicsItem *panel = item ? item->panel() : nullptr;
+    lastActivePanel = panel ? activePanel : nullptr;
     if (panel == activePanel || (!q->isActive() && !duringActivationEvent))
         return;
 
@@ -764,7 +764,7 @@ void QGraphicsScenePrivate::setActivePanelHelper(QGraphicsItem *item, bool durin
         if (QGraphicsItem *fi = activePanel->focusItem()) {
             // Remove focus from the current focus item.
             if (fi == q->focusItem())
-                setFocusItemHelper(0, Qt::ActiveWindowFocusReason, /* emitFocusChanged = */ false);
+                setFocusItemHelper(nullptr, Qt::ActiveWindowFocusReason, /* emitFocusChanged = */ false);
         }
 
         QEvent event(QEvent::WindowDeactivate);
@@ -841,7 +841,7 @@ void QGraphicsScenePrivate::setFocusItemHelper(QGraphicsItem *item,
     // accept input focus.
     if (item && (!(item->flags() & QGraphicsItem::ItemIsFocusable)
                  || !item->isVisible() || !item->isEnabled())) {
-        item = 0;
+        item = nullptr;
     }
 
     // Set focus on the scene if an item requests focus.
@@ -849,7 +849,7 @@ void QGraphicsScenePrivate::setFocusItemHelper(QGraphicsItem *item,
         q->setFocus(focusReason);
         if (item == focusItem) {
             if (emitFocusChanged)
-                emit q->focusItemChanged(focusItem, (QGraphicsItem *)0, focusReason);
+                emit q->focusItemChanged(focusItem, (QGraphicsItem *)nullptr, focusReason);
             return;
         }
     }
@@ -869,7 +869,7 @@ void QGraphicsScenePrivate::setFocusItemHelper(QGraphicsItem *item,
         }
 #endif //QT_NO_IM
 
-        focusItem = 0;
+        focusItem = nullptr;
         QFocusEvent event(QEvent::FocusOut, focusReason);
         sendEvent(lastFocusItem, &event);
     }
@@ -877,7 +877,7 @@ void QGraphicsScenePrivate::setFocusItemHelper(QGraphicsItem *item,
     // This handles the case that the item has been removed from the
     // scene in response to the FocusOut event.
     if (item && item->scene() != q)
-        item = 0;
+        item = nullptr;
 
     if (item)
         focusItem = item;
@@ -1039,7 +1039,7 @@ void QGraphicsScenePrivate::clearMouseGrabber()
 {
     if (!mouseGrabberItems.isEmpty())
         mouseGrabberItems.first()->ungrabMouse();
-    lastMouseGrabberItem = 0;
+    lastMouseGrabberItem = nullptr;
 }
 
 /*!
@@ -1365,10 +1365,10 @@ void QGraphicsScenePrivate::mousePressEventHandler(QGraphicsSceneMouseEvent *mou
 
     // Update window activation.
     QGraphicsItem *topItem = cachedItemsUnderMouse.value(0);
-    QGraphicsWidget *newActiveWindow = topItem ? topItem->window() : 0;
+    QGraphicsWidget *newActiveWindow = topItem ? topItem->window() : nullptr;
     if (newActiveWindow && newActiveWindow->isBlockedByModalPanel(&topItem)) {
         // pass activation to the blocking modal window
-        newActiveWindow = topItem ? topItem->window() : 0;
+        newActiveWindow = topItem ? topItem->window() : nullptr;
     }
 
     if (newActiveWindow != q->activeWindow())
@@ -1409,7 +1409,7 @@ void QGraphicsScenePrivate::mousePressEventHandler(QGraphicsSceneMouseEvent *mou
 
     // If nobody could take focus, clear it.
     if (!stickyFocus && !setFocus && !sceneModality)
-        q->setFocusItem(0, Qt::MouseFocusReason);
+        q->setFocusItem(nullptr, Qt::MouseFocusReason);
 
     // Any item will do.
     if (sceneModality && cachedItemsUnderMouse.isEmpty())
@@ -1694,7 +1694,7 @@ QGraphicsScene::~QGraphicsScene()
 
     // Remove this scene from all associated views.
     for (int j = 0; j < d->views.size(); ++j)
-        d->views.at(j)->setScene(0);
+        d->views.at(j)->setScene(nullptr);
 }
 
 /*!
@@ -2432,7 +2432,7 @@ QGraphicsItemGroup *QGraphicsScene::createItemGroup(const QList<QGraphicsItem *>
     }
 
     // Find the common ancestor for all items
-    QGraphicsItem *commonAncestor = 0;
+    QGraphicsItem *commonAncestor = nullptr;
     if (!ancestors.isEmpty()) {
         while (n < items.size()) {
             int commonIndex = -1;
@@ -2446,7 +2446,7 @@ QGraphicsItemGroup *QGraphicsScene::createItemGroup(const QList<QGraphicsItem *>
             } while ((parent = parent->parentItem()));
 
             if (commonIndex == -1) {
-                commonAncestor = 0;
+                commonAncestor = nullptr;
                 break;
             }
 
@@ -2545,7 +2545,7 @@ void QGraphicsScene::addItem(QGraphicsItem *item)
     // from this scene.
     if (QGraphicsItem *itemParent = item->d_ptr->parent) {
         if (itemParent->d_ptr->scene != this)
-            item->setParentItem(0);
+            item->setParentItem(nullptr);
     }
 
     // Add the item to this scene
@@ -2911,7 +2911,7 @@ QGraphicsSimpleTextItem *QGraphicsScene::addSimpleText(const QString &text, cons
 */
 QGraphicsProxyWidget *QGraphicsScene::addWidget(QWidget *widget, Qt::WindowFlags wFlags)
 {
-    QGraphicsProxyWidget *proxy = new QGraphicsProxyWidget(0, wFlags);
+    QGraphicsProxyWidget *proxy = new QGraphicsProxyWidget(nullptr, wFlags);
     proxy->setWidget(widget);
     addItem(proxy);
     return proxy;
@@ -2944,7 +2944,7 @@ void QGraphicsScene::removeItem(QGraphicsItem *item)
     const QVariant newSceneVariant(item->itemChange(QGraphicsItem::ItemSceneChange,
                                                     QVariant::fromValue<QGraphicsScene *>(0)));
     QGraphicsScene *targetScene = qvariant_cast<QGraphicsScene *>(newSceneVariant);
-    if (targetScene != 0 && targetScene != this) {
+    if (targetScene != nullptr && targetScene != this) {
         targetScene->addItem(item);
         return;
     }
@@ -3046,7 +3046,7 @@ void QGraphicsScene::clearFocus()
     if (d->hasFocus) {
         d->hasFocus = false;
         d->passiveFocusItem = d->focusItem;
-        setFocusItem(0, Qt::OtherFocusReason);
+        setFocusItem(nullptr, Qt::OtherFocusReason);
     }
 }
 
@@ -3492,7 +3492,7 @@ bool QGraphicsScene::event(QEvent *event)
                 // Deactivate the active panel (but keep it so we can
                 // reactivate it later).
                 QGraphicsItem *lastActivePanel = d->activePanel;
-                d->setActivePanelHelper(0, true);
+                d->setActivePanelHelper(nullptr, true);
                 d->lastActivePanel = lastActivePanel;
             } else {
                 // Activate all toplevel items.
@@ -3621,7 +3621,7 @@ void QGraphicsScene::contextMenuEvent(QGraphicsSceneContextMenuEvent *contextMen
 void QGraphicsScene::dragEnterEvent(QGraphicsSceneDragDropEvent *event)
 {
     Q_D(QGraphicsScene);
-    d->dragDropItem = 0;
+    d->dragDropItem = nullptr;
     d->lastDropAction = Qt::IgnoreAction;
     event->accept();
 }
@@ -3705,7 +3705,7 @@ void QGraphicsScene::dragMoveEvent(QGraphicsSceneDragDropEvent *event)
             QGraphicsSceneDragDropEvent dragLeave(QEvent::GraphicsSceneDragLeave);
             d->cloneDragDropEvent(&dragLeave, event);
             d->sendDragDropEvent(d->dragDropItem, &dragLeave);
-            d->dragDropItem = 0;
+            d->dragDropItem = nullptr;
         }
         // Propagate
         event->setDropAction(Qt::IgnoreAction);
@@ -3725,7 +3725,7 @@ void QGraphicsScene::dragLeaveEvent(QGraphicsSceneDragDropEvent *event)
     if (d->dragDropItem) {
         // Leave the last drag drop item
         d->sendDragDropEvent(d->dragDropItem, event);
-        d->dragDropItem = 0;
+        d->dragDropItem = nullptr;
     }
 }
 
@@ -3743,7 +3743,7 @@ void QGraphicsScene::dropEvent(QGraphicsSceneDragDropEvent *event)
     if (d->dragDropItem) {
         // Drop on the last drag drop item
         d->sendDragDropEvent(d->dragDropItem, event);
-        d->dragDropItem = 0;
+        d->dragDropItem = nullptr;
     }
 }
 
@@ -3793,7 +3793,7 @@ void QGraphicsScene::focusOutEvent(QFocusEvent *focusEvent)
     Q_D(QGraphicsScene);
     d->hasFocus = false;
     d->passiveFocusItem = d->focusItem;
-    setFocusItem(0, focusEvent->reason());
+    setFocusItem(nullptr, focusEvent->reason());
 
     // Remove all popups when the scene loses focus.
     if (!d->popupWidgets.isEmpty())
@@ -3825,7 +3825,7 @@ void QGraphicsScene::helpEvent(QGraphicsSceneHelpEvent *helpEvent)
     QList<QGraphicsItem *> itemsAtPos = d->itemsAtPosition(helpEvent->screenPos(),
                                                            helpEvent->scenePos(),
                                                            helpEvent->widget());
-    QGraphicsItem *toolTipItem = 0;
+    QGraphicsItem *toolTipItem = nullptr;
     for (int i = 0; i < itemsAtPos.size(); ++i) {
         QGraphicsItem *tmp = itemsAtPos.at(i);
         if (tmp->d_func()->isProxyWidget()) {
@@ -3883,7 +3883,7 @@ bool QGraphicsScenePrivate::dispatchHoverEvent(QGraphicsSceneHoverEvent *hoverEv
                                                 hoverEvent->widget());
     }
 
-    QGraphicsItem *item = 0;
+    QGraphicsItem *item = nullptr;
     for (int i = 0; i < cachedItemsUnderMouse.size(); ++i) {
         QGraphicsItem *tmp = cachedItemsUnderMouse.at(i);
         if (itemAcceptsHoverEvents_helper(tmp)) {
@@ -3894,13 +3894,13 @@ bool QGraphicsScenePrivate::dispatchHoverEvent(QGraphicsSceneHoverEvent *hoverEv
 
     // Find the common ancestor item for the new topmost hoverItem and the
     // last item in the hoverItem list.
-    QGraphicsItem *commonAncestorItem = (item && !hoverItems.isEmpty()) ? item->commonAncestorItem(hoverItems.constLast()) : 0;
+    QGraphicsItem *commonAncestorItem = (item && !hoverItems.isEmpty()) ? item->commonAncestorItem(hoverItems.constLast()) : nullptr;
     while (commonAncestorItem && !itemAcceptsHoverEvents_helper(commonAncestorItem))
         commonAncestorItem = commonAncestorItem->parentItem();
     if (commonAncestorItem && commonAncestorItem->panel() != item->panel()) {
         // The common ancestor isn't in the same panel as the two hovered
         // items.
-        commonAncestorItem = 0;
+        commonAncestorItem = nullptr;
     }
 
     // Check if the common ancestor item is known.
@@ -4130,7 +4130,7 @@ void QGraphicsScene::mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent)
             if (d->lastMouseGrabberItemHasImplicitMouseGrab)
                 d->mouseGrabberItems.constLast()->ungrabMouse();
         } else {
-            d->lastMouseGrabberItem = 0;
+            d->lastMouseGrabberItem = nullptr;
         }
 
         // Generate a hoverevent
@@ -4362,7 +4362,7 @@ static void _q_paintIntoCache(QPixmap *pix, QGraphicsItem *item, const QRegion &
     pixmapPainter.setWorldTransform(itemToPixmap, true);
 
     // Render.
-    _q_paintItem(item, &pixmapPainter, option, 0, false, painterStateProtection);
+    _q_paintItem(item, &pixmapPainter, option, nullptr, false, painterStateProtection);
     pixmapPainter.end();
 
     if (!subPix.isNull()) {
@@ -4756,7 +4756,7 @@ void QGraphicsScenePrivate::drawSubtreeRecursive(QGraphicsItem *item, QPainter *
         return;
 
     QTransform transform(Qt::Uninitialized);
-    QTransform *transformPtr = 0;
+    QTransform *transformPtr = nullptr;
     bool translateOnlyTransform = false;
 #define ENSURE_TRANSFORM_PTR \
     if (!transformPtr) { \
@@ -4866,7 +4866,7 @@ void QGraphicsScenePrivate::drawSubtreeRecursive(QGraphicsItem *item, QPainter *
 
         item->d_ptr->graphicsEffect->draw(painter);
         painter->setWorldTransform(restoreTransform);
-        sourced->info = 0;
+        sourced->info = nullptr;
     } else
 #endif // QT_CONFIG(graphicseffect)
     {
@@ -4944,7 +4944,7 @@ void QGraphicsScenePrivate::draw(QGraphicsItem *item, QPainter *painter, const Q
         Q_ASSERT(!(item->d_ptr->flags & QGraphicsItem::ItemHasNoContents));
         Q_ASSERT(transformPtr);
         item->d_ptr->initStyleOption(&styleOptionTmp, *transformPtr, exposedRegion
-                                     ? *exposedRegion : QRegion(), exposedRegion == 0);
+                                     ? *exposedRegion : QRegion(), exposedRegion == nullptr);
 
         const bool itemClipsToShape = item->d_ptr->flags & QGraphicsItem::ItemClipsToShape;
         bool restorePainterClip = false;
@@ -5330,7 +5330,7 @@ void QGraphicsScenePrivate::processDirtyItemsRecursive(QGraphicsItem *item, bool
         if (itemClipsChildrenToShape) {
             // Reset updateClip.
             for (int i = 0; i < views.size(); ++i)
-                views.at(i)->d_func()->setUpdateClip(0);
+                views.at(i)->d_func()->setUpdateClip(nullptr);
         }
     } else if (wasDirtyParentSceneTransform) {
         item->d_ptr->invalidateChildrenSceneTransform();
@@ -5386,7 +5386,7 @@ void QGraphicsScene::drawItems(QPainter *painter,
 
     // Determine view, expose and flags.
     QGraphicsView *view = widget ? qobject_cast<QGraphicsView *>(widget->parentWidget()) : 0;
-    QRegion *expose = 0;
+    QRegion *expose = nullptr;
     const quint32 oldRectAdjust = d->rectAdjust;
     if (view) {
         d->updateAll = false;
@@ -5470,7 +5470,7 @@ bool QGraphicsScene::focusNextPrevChild(bool next)
     }
 
     // The item must be a widget.
-    QGraphicsWidget *widget = 0;
+    QGraphicsWidget *widget = nullptr;
     if (!item) {
         widget = next ? d->tabFocusFirst : d->tabFocusFirst->d_func()->focusPrev;
     } else {
@@ -5486,7 +5486,7 @@ bool QGraphicsScene::focusNextPrevChild(bool next)
     // Run around the focus chain until we find a widget that can take tab focus.
     do {
         if (widget->flags() & QGraphicsItem::ItemIsFocusable
-            && widget->isEnabled() && widget->isVisibleTo(0)
+            && widget->isEnabled() && widget->isVisibleTo(nullptr)
             && (widget->focusPolicy() & Qt::TabFocus)
             && (!item || !item->isPanel() || item->isAncestorOf(widget))
             ) {
@@ -5771,7 +5771,7 @@ void QGraphicsScene::setActiveWindow(QGraphicsWidget *widget)
     }
 
     // Activate the widget's panel (all windows are panels).
-    QGraphicsItem *panel = widget ? widget->panel() : 0;
+    QGraphicsItem *panel = widget ? widget->panel() : nullptr;
     setActivePanel(panel);
 
     // Raise
@@ -5953,7 +5953,7 @@ void QGraphicsScenePrivate::touchEventHandler(QTouchEvent *sceneTouchEvent)
         const QTouchEvent::TouchPoint &touchPoint = sceneTouchEvent->touchPoints().at(i);
 
         // update state
-        QGraphicsItem *item = 0;
+        QGraphicsItem *item = nullptr;
         if (touchPoint.state() == Qt::TouchPointPressed) {
             if (sceneTouchEvent->device()->type() == QTouchDevice::TouchPad) {
                 // on touch-pad devices, send all touch points to the same item
@@ -6111,7 +6111,7 @@ bool QGraphicsScenePrivate::sendTouchBeginEvent(QGraphicsItem *origin, QTouchEve
 
         // If nobody could take focus, clear it.
         if (!stickyFocus && !setFocus)
-            q->setFocusItem(0, Qt::MouseFocusReason);
+            q->setFocusItem(nullptr, Qt::MouseFocusReason);
     }
 
     bool res = false;
@@ -6125,7 +6125,7 @@ bool QGraphicsScenePrivate::sendTouchBeginEvent(QGraphicsItem *origin, QTouchEve
         eventAccepted = touchEvent->isAccepted();
         if (itemForTouchPointId.value(touchEvent->touchPoints().first().id()) == 0) {
             // item was deleted
-            item = 0;
+            item = nullptr;
         } else {
             item->d_ptr->acceptedTouchBeginEvent = (res && eventAccepted);
         }
@@ -6259,7 +6259,7 @@ void QGraphicsScenePrivate::gestureTargetsAtHotSpots(const QSet<QGesture *> &ges
         if (!gesture->hasHotSpot())
             continue;
         const Qt::GestureType gestureType = gesture->gestureType();
-        QList<QGraphicsItem *> items = itemsAtPosition(QPoint(), gesture->d_func()->sceneHotSpot, 0);
+        QList<QGraphicsItem *> items = itemsAtPosition(QPoint(), gesture->d_func()->sceneHotSpot, nullptr);
         for (int j = 0; j < items.size(); ++j) {
             QGraphicsItem *item = items.at(j);
 
@@ -6331,7 +6331,7 @@ void QGraphicsScenePrivate::gestureEventHandler(QGestureEvent *event)
     if (!startedGestures.isEmpty()) {
         QSet<QGesture *> normalGestures; // that have just one target
         QSet<QGesture *> conflictedGestures; // that have multiple possible targets
-        gestureTargetsAtHotSpots(startedGestures, Qt::GestureFlag(0), &cachedItemGestures, 0,
+        gestureTargetsAtHotSpots(startedGestures, Qt::GestureFlag(0), &cachedItemGestures, nullptr,
                                  &normalGestures, &conflictedGestures);
         cachedTargetItems = cachedItemGestures.keys();
         std::sort(cachedTargetItems.begin(), cachedTargetItems.end(), qt_closestItemFirst);
@@ -6505,7 +6505,7 @@ void QGraphicsScenePrivate::gestureEventHandler(QGestureEvent *event)
             }
 
             gestureTargetsAtHotSpots(ignoredGestures, Qt::ReceivePartialGestures,
-                                     &cachedItemGestures, &targetsSet, 0, 0);
+                                     &cachedItemGestures, &targetsSet, nullptr, nullptr);
 
             cachedTargetItems = targetsSet.values();
             std::sort(cachedTargetItems.begin(), cachedTargetItems.end(), qt_closestItemFirst);
@@ -6545,7 +6545,7 @@ void QGraphicsScenePrivate::cancelGesturesForChildren(QGesture *original)
 {
     Q_ASSERT(original);
     QGraphicsItem *originalItem = gestureTargets.value(original);
-    if (originalItem == 0) // we only act on accepted gestures, which implies it has a target.
+    if (originalItem == nullptr) // we only act on accepted gestures, which implies it has a target.
         return;
 
     // iterate over all active gestures and for each find the owner
@@ -6568,13 +6568,13 @@ void QGraphicsScenePrivate::cancelGesturesForChildren(QGesture *original)
     QSet<QGesture *> almostCanceledGestures = canceledGestures;
     QSet<QGesture *>::Iterator setIter;
     while (!almostCanceledGestures.isEmpty()) {
-        QGraphicsObject *target = 0;
+        QGraphicsObject *target = nullptr;
         QSet<QGesture*> gestures;
         setIter = almostCanceledGestures.begin();
         // sort per target item
         while (setIter != almostCanceledGestures.end()) {
             QGraphicsObject *item = gestureTargets.value(*setIter);
-            if (target == 0)
+            if (target == nullptr)
                 target = item;
             if (target == item) {
                 gestures << *setIter;
@@ -6598,7 +6598,7 @@ void QGraphicsScenePrivate::cancelGesturesForChildren(QGesture *original)
                 if (!g->hasHotSpot())
                     continue;
 
-                QList<QGraphicsItem *> items = itemsAtPosition(QPoint(), g->d_func()->sceneHotSpot, 0);
+                QList<QGraphicsItem *> items = itemsAtPosition(QPoint(), g->d_func()->sceneHotSpot, nullptr);
                 for (int j = 0; j < items.size(); ++j) {
                     QGraphicsObject *item = items.at(j)->toGraphicsObject();
                     if (!item)
diff --git a/src/widgets/graphicsview/qgraphicssceneevent.cpp b/src/widgets/graphicsview/qgraphicssceneevent.cpp
index 768dd07d4e..048ea6dc7d 100644
--- a/src/widgets/graphicsview/qgraphicssceneevent.cpp
+++ b/src/widgets/graphicsview/qgraphicssceneevent.cpp
@@ -278,8 +278,8 @@ class QGraphicsSceneEventPrivate
 {
 public:
     inline QGraphicsSceneEventPrivate()
-        : widget(0),
-          q_ptr(0)
+        : widget(nullptr),
+          q_ptr(nullptr)
     { }
 
     inline virtual ~QGraphicsSceneEventPrivate()
@@ -1290,7 +1290,7 @@ class QGraphicsSceneDragDropEventPrivate : public QGraphicsSceneEventPrivate
     Q_DECLARE_PUBLIC(QGraphicsSceneDragDropEvent)
 public:
     inline QGraphicsSceneDragDropEventPrivate()
-        : source(0), mimeData(0)
+        : source(nullptr), mimeData(nullptr)
     { }
 
     QPointF pos;
diff --git a/src/widgets/graphicsview/qgraphicstransform.cpp b/src/widgets/graphicsview/qgraphicstransform.cpp
index 0f0d9aaddc..fa763de05d 100644
--- a/src/widgets/graphicsview/qgraphicstransform.cpp
+++ b/src/widgets/graphicsview/qgraphicstransform.cpp
@@ -112,7 +112,7 @@ void QGraphicsTransformPrivate::setItem(QGraphicsItem *i)
         Q_ASSERT(d_ptr->transformData);
         d_ptr->transformData->graphicsTransforms.removeAll(q);
         d_ptr->dirtySceneTransform = 1;
-        item = 0;
+        item = nullptr;
     }
 
     item = i;
@@ -138,7 +138,7 @@ QGraphicsTransform::QGraphicsTransform(QObject *parent)
 QGraphicsTransform::~QGraphicsTransform()
 {
     Q_D(QGraphicsTransform);
-    d->setItem(0);
+    d->setItem(nullptr);
 }
 
 /*!
diff --git a/src/widgets/graphicsview/qgraphicsview.cpp b/src/widgets/graphicsview/qgraphicsview.cpp
index 4c270b1af2..7589a1ebbd 100644
--- a/src/widgets/graphicsview/qgraphicsview.cpp
+++ b/src/widgets/graphicsview/qgraphicsview.cpp
@@ -352,7 +352,7 @@ QGraphicsViewPrivate::QGraphicsViewPrivate()
       alignment(Qt::AlignCenter),
       transformationAnchor(QGraphicsView::AnchorViewCenter), resizeAnchor(QGraphicsView::NoAnchor),
       viewportUpdateMode(QGraphicsView::MinimalViewportUpdate),
-      scene(0),
+      scene(nullptr),
 #if QT_CONFIG(rubberband)
       rubberBanding(false),
       rubberBandSelectionMode(Qt::IntersectsItemShape),
@@ -362,7 +362,7 @@ QGraphicsViewPrivate::QGraphicsViewPrivate()
 #ifndef QT_NO_CURSOR
       hasStoredOriginalCursor(false),
 #endif
-      lastDragDropEvent(0),
+      lastDragDropEvent(nullptr),
       updateSceneSlotReimplementedChecked(false)
 {
     styleOptions.reserve(QGRAPHICSVIEW_PREALLOC_STYLE_OPTIONS);
@@ -384,7 +384,7 @@ void QGraphicsViewPrivate::recalculateContentSize()
     int height = maxSize.height();
     QRectF viewRect = matrix.mapRect(q->sceneRect());
 
-    bool frameOnlyAround = (q->style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, 0, q));
+    bool frameOnlyAround = (q->style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, nullptr, q));
     if (frameOnlyAround) {
         if (hbarpolicy == Qt::ScrollBarAlwaysOn)
             height -= frameWidth * 2;
@@ -394,7 +394,7 @@ void QGraphicsViewPrivate::recalculateContentSize()
 
     // Adjust the maximum width and height of the viewport based on the width
     // of visible scroll bars.
-    int scrollBarExtent = q->style()->pixelMetric(QStyle::PM_ScrollBarExtent, 0, q);
+    int scrollBarExtent = q->style()->pixelMetric(QStyle::PM_ScrollBarExtent, nullptr, q);
     if (frameOnlyAround)
         scrollBarExtent += frameWidth * 2;
 
@@ -1162,7 +1162,7 @@ QList<QGraphicsItem *> QGraphicsViewPrivate::findItems(const QRegion &exposedReg
 void QGraphicsViewPrivate::updateInputMethodSensitivity()
 {
     Q_Q(QGraphicsView);
-    QGraphicsItem *focusItem = 0;
+    QGraphicsItem *focusItem = nullptr;
     bool enabled = scene && (focusItem = scene->focusItem())
                    && (focusItem->d_ptr->flags & QGraphicsItem::ItemAcceptsInputMethod);
     q->setAttribute(Qt::WA_InputMethodEnabled, enabled);
@@ -1174,7 +1174,7 @@ void QGraphicsViewPrivate::updateInputMethodSensitivity()
     }
 
     QGraphicsProxyWidget *proxy = focusItem->d_ptr->isWidget && focusItem->d_ptr->isProxyWidget()
-                                    ? static_cast<QGraphicsProxyWidget *>(focusItem) : 0;
+                                    ? static_cast<QGraphicsProxyWidget *>(focusItem) : nullptr;
     if (!proxy) {
         q->setInputMethodHints(focusItem->inputMethodHints());
     } else if (QWidget *widget = proxy->widget()) {
@@ -1192,7 +1192,7 @@ void QGraphicsViewPrivate::updateInputMethodSensitivity()
 QGraphicsView::QGraphicsView(QWidget *parent)
     : QAbstractScrollArea(*new QGraphicsViewPrivate, parent)
 {
-    setViewport(0);
+    setViewport(nullptr);
     setAcceptDrops(true);
     setBackgroundRole(QPalette::Base);
     // Investigate leaving these disabled by default.
@@ -1208,7 +1208,7 @@ QGraphicsView::QGraphicsView(QGraphicsScene *scene, QWidget *parent)
     : QAbstractScrollArea(*new QGraphicsViewPrivate, parent)
 {
     setScene(scene);
-    setViewport(0);
+    setViewport(nullptr);
     setAcceptDrops(true);
     setBackgroundRole(QPalette::Base);
     // Investigate leaving these disabled by default.
@@ -1222,7 +1222,7 @@ QGraphicsView::QGraphicsView(QGraphicsScene *scene, QWidget *parent)
 QGraphicsView::QGraphicsView(QGraphicsViewPrivate &dd, QWidget *parent)
   : QAbstractScrollArea(dd, parent)
 {
-    setViewport(0);
+    setViewport(nullptr);
     setAcceptDrops(true);
     setBackgroundRole(QPalette::Base);
     // Investigate leaving these disabled by default.
@@ -2374,7 +2374,7 @@ QGraphicsItem *QGraphicsView::itemAt(const QPoint &pos) const
 {
     Q_D(const QGraphicsView);
     if (!d->scene)
-        return 0;
+        return nullptr;
     const QList<QGraphicsItem *> itemsAtPos = items(pos);
     return itemsAtPos.isEmpty() ? 0 : itemsAtPos.first();
 }
@@ -2888,7 +2888,7 @@ bool QGraphicsView::viewportEvent(QEvent *event)
         }
         d->useLastMouseEvent = false;
         // a hack to pass a viewport pointer to the scene inside the leave event
-        Q_ASSERT(event->d == 0);
+        Q_ASSERT(event->d == nullptr);
         QScopedValueRollback<QEventPrivate *> rb(event->d);
         event->d = reinterpret_cast<QEventPrivate *>(viewport());
         QCoreApplication::sendEvent(d->scene, event);
@@ -3019,7 +3019,7 @@ void QGraphicsView::dropEvent(QDropEvent *event)
         event->setDropAction(sceneEvent.dropAction());
 
     delete d->lastDragDropEvent;
-    d->lastDragDropEvent = 0;
+    d->lastDragDropEvent = nullptr;
 }
 
 /*!
@@ -3077,7 +3077,7 @@ void QGraphicsView::dragLeaveEvent(QDragLeaveEvent *event)
     sceneEvent.setWidget(d->lastDragDropEvent->widget());
     sceneEvent.setSource(d->lastDragDropEvent->source());
     delete d->lastDragDropEvent;
-    d->lastDragDropEvent = 0;
+    d->lastDragDropEvent = nullptr;
 
     // Send it to the scene.
     QCoreApplication::sendEvent(d->scene, &sceneEvent);
@@ -3525,7 +3525,7 @@ void QGraphicsView::paintEvent(QPaintEvent *event)
             d->scene->d_func()->rectAdjust = 1;
         else
             d->scene->d_func()->rectAdjust = 2;
-        d->scene->d_func()->drawItems(&painter, viewTransformed ? &viewTransform : 0,
+        d->scene->d_func()->drawItems(&painter, viewTransformed ? &viewTransform : nullptr,
                                       &d->exposedRegion, viewport());
         d->scene->d_func()->rectAdjust = oldRectAdjust;
         // Make sure the painter's world transform is restored correctly when
@@ -3794,7 +3794,7 @@ void QGraphicsView::drawItems(QPainter *painter, int numItems,
 {
     Q_D(QGraphicsView);
     if (d->scene) {
-        QWidget *widget = painter->device() == viewport() ? viewport() : 0;
+        QWidget *widget = painter->device() == viewport() ? viewport() : nullptr;
         d->scene->drawItems(painter, numItems, items, options, widget);
     }
 }
diff --git a/src/widgets/graphicsview/qgraphicswidget.cpp b/src/widgets/graphicsview/qgraphicswidget.cpp
index cf041b9817..1035ed3575 100644
--- a/src/widgets/graphicsview/qgraphicswidget.cpp
+++ b/src/widgets/graphicsview/qgraphicswidget.cpp
@@ -172,7 +172,7 @@ QT_BEGIN_NAMESPACE
     window, a tool, a popup, etc).
 */
 QGraphicsWidget::QGraphicsWidget(QGraphicsItem *parent, Qt::WindowFlags wFlags)
-    : QGraphicsObject(*new QGraphicsWidgetPrivate, 0), QGraphicsLayoutItem(0, false)
+    : QGraphicsObject(*new QGraphicsWidgetPrivate, nullptr), QGraphicsLayoutItem(nullptr, false)
 {
     Q_D(QGraphicsWidget);
     d->init(parent, wFlags);
@@ -184,7 +184,7 @@ QGraphicsWidget::QGraphicsWidget(QGraphicsItem *parent, Qt::WindowFlags wFlags)
     Constructs a new QGraphicsWidget, using \a dd as parent.
 */
 QGraphicsWidget::QGraphicsWidget(QGraphicsWidgetPrivate &dd, QGraphicsItem *parent, Qt::WindowFlags wFlags)
-    : QGraphicsObject(dd, 0), QGraphicsLayoutItem(0, false)
+    : QGraphicsObject(dd, nullptr), QGraphicsLayoutItem(nullptr, false)
 {
     Q_D(QGraphicsWidget);
     d->init(parent, wFlags);
@@ -241,7 +241,7 @@ QGraphicsWidget::~QGraphicsWidget()
     if (QGraphicsScene *scn = scene()) {
         QGraphicsScenePrivate *sceneD = scn->d_func();
         if (sceneD->tabFocusFirst == this)
-            sceneD->tabFocusFirst = (d->focusNext == this ? 0 : d->focusNext);
+            sceneD->tabFocusFirst = (d->focusNext == this ? nullptr : d->focusNext);
     }
     d->focusPrev->d_func()->focusNext = d->focusNext;
     d->focusNext->d_func()->focusPrev = d->focusPrev;
@@ -263,15 +263,15 @@ QGraphicsWidget::~QGraphicsWidget()
             if (item->isWidget()) {
                 QGraphicsWidget *widget = static_cast<QGraphicsWidget *>(item);
                 if (widget->parentLayoutItem() == d->layout)
-                    widget->setParentLayoutItem(0);
+                    widget->setParentLayoutItem(nullptr);
             }
         }
-        d->layout = 0;
+        d->layout = nullptr;
         delete temp;
     }
 
     // Remove this graphics widget from widgetStyles
-    widgetStyles()->setStyleForWidget(this, 0);
+    widgetStyles()->setStyleForWidget(this, nullptr);
 
     // Unset the parent here, when we're still a QGraphicsWidget.
     // It is otherwise done in ~QGraphicsItem() where we'd be
@@ -942,7 +942,7 @@ QStyle *QGraphicsWidget::style() const
 */
 void QGraphicsWidget::setStyle(QStyle *style)
 {
-    setAttribute(Qt::WA_SetStyle, style != 0);
+    setAttribute(Qt::WA_SetStyle, style != nullptr);
     widgetStyles()->setStyleForWidget(this, style);
 
     // Deliver StyleChange to the widget itself (doesn't propagate).
@@ -1557,7 +1557,7 @@ bool QGraphicsWidget::focusNextPrevChild(bool next)
 {
     Q_D(QGraphicsWidget);
     // Let the parent's focusNextPrevChild implementation decide what to do.
-    QGraphicsWidget *parent = 0;
+    QGraphicsWidget *parent = nullptr;
     if (!isWindow() && (parent = parentWidget()))
         return parent->focusNextPrevChild(next);
     if (!d->scene)
@@ -1995,7 +1995,7 @@ void QGraphicsWidget::setShortcutAutoRepeat(int id, bool enabled)
 */
 void QGraphicsWidget::addAction(QAction *action)
 {
-    insertAction(0, action);
+    insertAction(nullptr, action);
 }
 
 /*!
@@ -2012,7 +2012,7 @@ void QGraphicsWidget::addActions(QList<QAction *> actions)
 #endif
 {
     for (int i = 0; i < actions.count(); ++i)
-        insertAction(0, actions.at(i));
+        insertAction(nullptr, actions.at(i));
 }
 
 /*!
@@ -2041,7 +2041,7 @@ void QGraphicsWidget::insertAction(QAction *before, QAction *action)
 
     int pos = d->actions.indexOf(before);
     if (pos < 0) {
-        before = 0;
+        before = nullptr;
         pos = d->actions.size();
     }
     d->actions.insert(pos, action);
@@ -2346,7 +2346,7 @@ void QGraphicsWidget::paintWindowFrame(QPainter *painter, const QStyleOptionGrap
 
     frameOptions.palette.setCurrentColorGroup(isActive ? QPalette::Active : QPalette::Normal);
     frameOptions.rect = windowFrameRect;
-    frameOptions.lineWidth = style()->pixelMetric(QStyle::PM_MdiSubWindowFrameWidth, 0, widget);
+    frameOptions.lineWidth = style()->pixelMetric(QStyle::PM_MdiSubWindowFrameWidth, nullptr, widget);
     frameOptions.midLineWidth = 1;
     style()->drawPrimitive(QStyle::PE_FrameWindow, &frameOptions, painter, widget);
 
diff --git a/src/widgets/graphicsview/qgraphicswidget_p.cpp b/src/widgets/graphicsview/qgraphicswidget_p.cpp
index 0156faf8e4..e6f39d6803 100644
--- a/src/widgets/graphicsview/qgraphicswidget_p.cpp
+++ b/src/widgets/graphicsview/qgraphicswidget_p.cpp
@@ -322,7 +322,7 @@ void QGraphicsWidgetPrivate::initStyleOptionTitleBar(QStyleOptionTitleBar *optio
         option->titleBarState = Qt::WindowNoState;
     }
     QFont windowTitleFont = QApplication::font("QMdiSubWindowTitleBar");
-    QRect textRect = q->style()->subControlRect(QStyle::CC_TitleBar, option, QStyle::SC_TitleBarLabel, 0);
+    QRect textRect = q->style()->subControlRect(QStyle::CC_TitleBar, option, QStyle::SC_TitleBarLabel, nullptr);
     option->text = QFontMetrics(windowTitleFont).elidedText(
         windowData->windowTitle, Qt::ElideRight, textRect.width());
 }
@@ -690,7 +690,7 @@ void QGraphicsWidgetPrivate::windowFrameHoverMoveEvent(QGraphicsSceneHoverEvent
             break;
         case Qt::TitleBarArea:
             windowData->buttonRect = q->style()->subControlRect(
-                QStyle::CC_TitleBar, &bar, QStyle::SC_TitleBarCloseButton, 0);
+                QStyle::CC_TitleBar, &bar, QStyle::SC_TitleBarCloseButton, nullptr);
             if (windowData->buttonRect.contains(pos.toPoint()))
                 windowData->buttonMouseOver = true;
             event->ignore();
@@ -707,7 +707,7 @@ void QGraphicsWidgetPrivate::windowFrameHoverMoveEvent(QGraphicsSceneHoverEvent
     Q_UNUSED(cursorShape);
 #endif
     // update buttons if we hover over them
-    windowData->hoveredSubControl = q->style()->hitTestComplexControl(QStyle::CC_TitleBar, &bar, pos.toPoint(), 0);
+    windowData->hoveredSubControl = q->style()->hitTestComplexControl(QStyle::CC_TitleBar, &bar, pos.toPoint(), nullptr);
     if (windowData->hoveredSubControl != QStyle::SC_TitleBarCloseButton)
         windowData->hoveredSubControl = QStyle::SC_TitleBarLabel;
 
@@ -781,7 +781,7 @@ void QGraphicsWidgetPrivate::fixFocusChainBeforeReparenting(QGraphicsWidget *new
 
     if (!parent && oldScene && oldScene != newScene && oldScene->d_func()->tabFocusFirst == q) {
         // detach from old scene's top level focus chain.
-        oldScene->d_func()->tabFocusFirst = (focusAfter != q) ? focusAfter : 0;
+        oldScene->d_func()->tabFocusFirst = (focusAfter != q) ? focusAfter : nullptr;
     }
 
     // detach from current focus chain; skip this widget subtree.
diff --git a/src/widgets/graphicsview/qsimplex_p.cpp b/src/widgets/graphicsview/qsimplex_p.cpp
index e18f1fa4c4..38c2df5fc6 100644
--- a/src/widgets/graphicsview/qsimplex_p.cpp
+++ b/src/widgets/graphicsview/qsimplex_p.cpp
@@ -76,7 +76,7 @@ QT_BEGIN_NAMESPACE
 /*!
   \internal
 */
-QSimplex::QSimplex() : objective(0), rows(0), columns(0), firstArtificial(0), matrix(0)
+QSimplex::QSimplex() : objective(nullptr), rows(0), columns(0), firstArtificial(0), matrix(nullptr)
 {
 }
 
@@ -93,7 +93,7 @@ QSimplex::~QSimplex()
 */
 void QSimplex::clearDataStructures()
 {
-    if (matrix == 0)
+    if (matrix == nullptr)
         return;
 
     // Matrix
@@ -101,7 +101,7 @@ void QSimplex::clearDataStructures()
     columns = 0;
     firstArtificial = 0;
     free(matrix);
-    matrix = 0;
+    matrix = nullptr;
 
     // Constraints
     for (int i = 0; i < constraints.size(); ++i) {
@@ -113,7 +113,7 @@ void QSimplex::clearDataStructures()
 
     // Other
     variables.clear();
-    objective = 0;
+    objective = nullptr;
 }
 
 /*!
@@ -195,7 +195,7 @@ bool QSimplex::setConstraints(const QList<QSimplexConstraint *> &newConstraints)
         QSimplexVariable *artificial;
 
         Q_ASSERT(constraints[i]->helper.first == 0);
-        Q_ASSERT(constraints[i]->artificial == 0);
+        Q_ASSERT(constraints[i]->artificial == nullptr);
 
         switch(constraints[i]->ratio) {
         case QSimplexConstraint::LessOrEqual:
diff --git a/src/widgets/itemviews/qabstractitemdelegate.cpp b/src/widgets/itemviews/qabstractitemdelegate.cpp
index eecc18e5c7..bb47881c03 100644
--- a/src/widgets/itemviews/qabstractitemdelegate.cpp
+++ b/src/widgets/itemviews/qabstractitemdelegate.cpp
@@ -255,7 +255,7 @@ QWidget *QAbstractItemDelegate::createEditor(QWidget *,
                                              const QStyleOptionViewItem &,
                                              const QModelIndex &) const
 {
-    return 0;
+    return nullptr;
 }
 
 
diff --git a/src/widgets/itemviews/qabstractitemview.cpp b/src/widgets/itemviews/qabstractitemview.cpp
index b1557e9af4..67c01adea7 100644
--- a/src/widgets/itemviews/qabstractitemview.cpp
+++ b/src/widgets/itemviews/qabstractitemview.cpp
@@ -77,13 +77,13 @@ QT_BEGIN_NAMESPACE
 
 QAbstractItemViewPrivate::QAbstractItemViewPrivate()
     :   model(QAbstractItemModelPrivate::staticEmptyModel()),
-        itemDelegate(0),
-        selectionModel(0),
+        itemDelegate(nullptr),
+        selectionModel(nullptr),
         ctrlDragSelectionFlag(QItemSelectionModel::NoUpdate),
         noSelectionOnMousePress(false),
         selectionMode(QAbstractItemView::ExtendedSelection),
         selectionBehavior(QAbstractItemView::SelectItems),
-        currentlyCommittingEditor(0),
+        currentlyCommittingEditor(nullptr),
         pressedModifiers(Qt::NoModifier),
         pressedPosition(QPoint(-1, -1)),
         pressedAlreadySelected(false),
@@ -145,8 +145,8 @@ void QAbstractItemViewPrivate::init()
 
     q->setAttribute(Qt::WA_InputMethodEnabled);
 
-    verticalScrollMode = static_cast<QAbstractItemView::ScrollMode>(q->style()->styleHint(QStyle::SH_ItemView_ScrollMode, 0, q, 0));
-    horizontalScrollMode = static_cast<QAbstractItemView::ScrollMode>(q->style()->styleHint(QStyle::SH_ItemView_ScrollMode, 0, q, 0));
+    verticalScrollMode = static_cast<QAbstractItemView::ScrollMode>(q->style()->styleHint(QStyle::SH_ItemView_ScrollMode, nullptr, q, nullptr));
+    horizontalScrollMode = static_cast<QAbstractItemView::ScrollMode>(q->style()->styleHint(QStyle::SH_ItemView_ScrollMode, nullptr, q, nullptr));
 }
 
 void QAbstractItemViewPrivate::setHoverIndex(const QPersistentModelIndex &index)
@@ -757,7 +757,7 @@ void QAbstractItemView::setModel(QAbstractItemModel *model)
 QAbstractItemModel *QAbstractItemView::model() const
 {
     Q_D(const QAbstractItemView);
-    return (d->model == QAbstractItemModelPrivate::staticEmptyModel() ? 0 : d->model);
+    return (d->model == QAbstractItemModelPrivate::staticEmptyModel() ? nullptr : d->model);
 }
 
 /*!
@@ -915,7 +915,7 @@ QVariant QAbstractItemView::inputMethodQuery(Qt::InputMethodQuery query) const
 void QAbstractItemView::setItemDelegateForRow(int row, QAbstractItemDelegate *delegate)
 {
     Q_D(QAbstractItemView);
-    if (QAbstractItemDelegate *rowDelegate = d->rowDelegates.value(row, 0)) {
+    if (QAbstractItemDelegate *rowDelegate = d->rowDelegates.value(row, nullptr)) {
         if (d->delegateRefCount(rowDelegate) == 1) {
             disconnect(rowDelegate, SIGNAL(closeEditor(QWidget*,QAbstractItemDelegate::EndEditHint)),
                        this, SLOT(closeEditor(QWidget*,QAbstractItemDelegate::EndEditHint)));
@@ -949,7 +949,7 @@ void QAbstractItemView::setItemDelegateForRow(int row, QAbstractItemDelegate *de
 QAbstractItemDelegate *QAbstractItemView::itemDelegateForRow(int row) const
 {
     Q_D(const QAbstractItemView);
-    return d->rowDelegates.value(row, 0);
+    return d->rowDelegates.value(row, nullptr);
 }
 
 /*!
@@ -975,7 +975,7 @@ QAbstractItemDelegate *QAbstractItemView::itemDelegateForRow(int row) const
 void QAbstractItemView::setItemDelegateForColumn(int column, QAbstractItemDelegate *delegate)
 {
     Q_D(QAbstractItemView);
-    if (QAbstractItemDelegate *columnDelegate = d->columnDelegates.value(column, 0)) {
+    if (QAbstractItemDelegate *columnDelegate = d->columnDelegates.value(column, nullptr)) {
         if (d->delegateRefCount(columnDelegate) == 1) {
             disconnect(columnDelegate, SIGNAL(closeEditor(QWidget*,QAbstractItemDelegate::EndEditHint)),
                        this, SLOT(closeEditor(QWidget*,QAbstractItemDelegate::EndEditHint)));
@@ -1009,7 +1009,7 @@ void QAbstractItemView::setItemDelegateForColumn(int column, QAbstractItemDelega
 QAbstractItemDelegate *QAbstractItemView::itemDelegateForColumn(int column) const
 {
     Q_D(const QAbstractItemView);
-    return d->columnDelegates.value(column, 0);
+    return d->columnDelegates.value(column, nullptr);
 }
 
 /*!
@@ -1084,7 +1084,7 @@ void QAbstractItemView::setCurrentIndex(const QModelIndex &index)
 {
     Q_D(QAbstractItemView);
     if (d->selectionModel && (!index.isValid() || d->isIndexEnabled(index))) {
-        QItemSelectionModel::SelectionFlags command = selectionCommand(index, 0);
+        QItemSelectionModel::SelectionFlags command = selectionCommand(index, nullptr);
         d->selectionModel->setCurrentIndex(index, command);
         d->currentIndexSet = true;
         if ((command & QItemSelectionModel::Current) == 0)
@@ -1201,7 +1201,7 @@ void QAbstractItemView::edit(const QModelIndex &index)
     Q_D(QAbstractItemView);
     if (Q_UNLIKELY(!d->isIndexValid(index)))
         qWarning("edit: index was invalid");
-    if (Q_UNLIKELY(!edit(index, AllEditTriggers, 0)))
+    if (Q_UNLIKELY(!edit(index, AllEditTriggers, nullptr)))
         qWarning("edit: editing failed");
 }
 
@@ -1286,7 +1286,7 @@ QAbstractItemView::ScrollMode QAbstractItemView::verticalScrollMode() const
 
 void QAbstractItemView::resetVerticalScrollMode()
 {
-    auto sm = static_cast<ScrollMode>(style()->styleHint(QStyle::SH_ItemView_ScrollMode, 0, this, 0));
+    auto sm = static_cast<ScrollMode>(style()->styleHint(QStyle::SH_ItemView_ScrollMode, nullptr, this, nullptr));
     setVerticalScrollMode(sm);
     d_func()->verticalScrollModeSet = false;
 }
@@ -1323,7 +1323,7 @@ QAbstractItemView::ScrollMode QAbstractItemView::horizontalScrollMode() const
 
 void QAbstractItemView::resetHorizontalScrollMode()
 {
-    auto sm = static_cast<ScrollMode>(style()->styleHint(QStyle::SH_ItemView_ScrollMode, 0, this, 0));
+    auto sm = static_cast<ScrollMode>(style()->styleHint(QStyle::SH_ItemView_ScrollMode, nullptr, this, nullptr));
     setHorizontalScrollMode(sm);
     d_func()->horizontalScrollModeSet = false;
 }
@@ -1964,7 +1964,7 @@ void QAbstractItemView::mouseDoubleClickEvent(QMouseEvent *event)
     QPersistentModelIndex persistent = index;
     emit doubleClicked(persistent);
     if ((event->button() == Qt::LeftButton) && !edit(persistent, DoubleClicked, event)
-        && !style()->styleHint(QStyle::SH_ItemView_ActivateItemOnSingleClick, 0, this))
+        && !style()->styleHint(QStyle::SH_ItemView_ActivateItemOnSingleClick, nullptr, this))
         emit activated(persistent);
     d->pressedIndex = QModelIndex();
 }
@@ -2388,7 +2388,7 @@ void QAbstractItemView::keyPressEvent(QKeyEvent *event)
             setFocus();
         QItemSelectionModel::SelectionFlags command = selectionCommand(newCurrent, event);
         if (command != QItemSelectionModel::NoUpdate
-             || style()->styleHint(QStyle::SH_ItemView_MovementWithoutUpdatingSelection, 0, this)) {
+             || style()->styleHint(QStyle::SH_ItemView_MovementWithoutUpdatingSelection, nullptr, this)) {
             // note that we don't check if the new current index is enabled because moveCursor() makes sure it is
             if (command & QItemSelectionModel::Current) {
                 d->selectionModel->setCurrentIndex(newCurrent, QItemSelectionModel::NoUpdate);
@@ -2654,7 +2654,7 @@ bool QAbstractItemView::edit(const QModelIndex &index, EditTrigger trigger, QEve
     if (!d->isIndexValid(index))
         return false;
 
-    if (QWidget *w = (d->persistent.isEmpty() ? static_cast<QWidget*>(0) : d->editorForIndex(index).widget.data())) {
+    if (QWidget *w = (d->persistent.isEmpty() ? static_cast<QWidget*>(nullptr) : d->editorForIndex(index).widget.data())) {
         if (w->focusPolicy() == Qt::NoFocus)
             return false;
         w->setFocus();
@@ -2692,7 +2692,7 @@ bool QAbstractItemView::edit(const QModelIndex &index, EditTrigger trigger, QEve
     if (trigger == SelectedClicked)
         d->delayedEditing.start(QApplication::doubleClickInterval(), this);
     else
-        d->openEditor(index, d->shouldForwardEvent(trigger, event) ? event : 0);
+        d->openEditor(index, d->shouldForwardEvent(trigger, event) ? event : nullptr);
 
     return true;
 }
@@ -2909,7 +2909,7 @@ void QAbstractItemView::commitData(QWidget *editor)
     editor->removeEventFilter(delegate);
     delegate->setModelData(editor, d->model, index);
     editor->installEventFilter(delegate);
-    d->currentlyCommittingEditor = 0;
+    d->currentlyCommittingEditor = nullptr;
 }
 
 /*!
@@ -3260,7 +3260,7 @@ QWidget* QAbstractItemView::indexWidget(const QModelIndex &index) const
         if (QWidget *editor = d->editorForIndex(index).widget.data())
             return editor;
 
-    return 0;
+    return nullptr;
 }
 
 /*!
@@ -3673,7 +3673,7 @@ void QAbstractItemView::currentChanged(const QModelIndex &current, const QModelI
             if (d->autoScroll)
                 scrollTo(current);
             update(current);
-            edit(current, CurrentChanged, 0);
+            edit(current, CurrentChanged, nullptr);
             if (current.row() == (d->model->rowCount(d->root) - 1))
                 d->fetchMore();
         } else {
@@ -3737,7 +3737,7 @@ QStyleOptionViewItem QAbstractItemView::viewOptions() const
     if (d->iconSize.isValid()) {
         option.decorationSize = d->iconSize;
     } else {
-        int pm = style()->pixelMetric(QStyle::PM_SmallIconSize, 0, this);
+        int pm = style()->pixelMetric(QStyle::PM_SmallIconSize, nullptr, this);
         option.decorationSize = QSize(pm, pm);
     }
     option.decorationPosition = QStyleOptionViewItem::Left;
@@ -3745,7 +3745,7 @@ QStyleOptionViewItem QAbstractItemView::viewOptions() const
     option.displayAlignment = Qt::AlignLeft|Qt::AlignVCenter;
     option.textElideMode = d->textElideMode;
     option.rect = QRect();
-    option.showDecorationSelected = style()->styleHint(QStyle::SH_ItemView_ShowDecorationSelected, 0, this);
+    option.showDecorationSelected = style()->styleHint(QStyle::SH_ItemView_ShowDecorationSelected, nullptr, this);
     if (d->wrapItemText)
         option.features = QStyleOptionViewItem::WrapText;
     option.locale = locale();
@@ -4231,7 +4231,7 @@ QWidget *QAbstractItemViewPrivate::editor(const QModelIndex &index,
     if (!w) {
         QAbstractItemDelegate *delegate = delegateForIndex(index);
         if (!delegate)
-            return 0;
+            return nullptr;
         w = delegate->createEditor(viewport, options, index);
         if (w) {
             w->installEventFilter(delegate);
diff --git a/src/widgets/itemviews/qcolumnview.cpp b/src/widgets/itemviews/qcolumnview.cpp
index a4eed2d885..4d0161025c 100644
--- a/src/widgets/itemviews/qcolumnview.cpp
+++ b/src/widgets/itemviews/qcolumnview.cpp
@@ -142,7 +142,7 @@ void QColumnView::setResizeGripsVisible(bool visible)
             connect(grip, SIGNAL(gripMoved(int)), this, SLOT(_q_gripMoved(int)));
         } else {
             QWidget *widget = view->cornerWidget();
-            view->setCornerWidget(0);
+            view->setCornerWidget(nullptr);
             widget->deleteLater();
         }
     }
@@ -327,7 +327,7 @@ void QColumnView::scrollTo(const QModelIndex &index, ScrollHint hint)
     }
 
 #if QT_CONFIG(animation)
-    if (const int animationDuration = style()->styleHint(QStyle::SH_Widget_Animation_Duration, 0, this)) {
+    if (const int animationDuration = style()->styleHint(QStyle::SH_Widget_Animation_Duration, nullptr, this)) {
         d->currentAnimation.setDuration(animationDuration);
         d->currentAnimation.setEndValue(newScrollbarValue);
         d->currentAnimation.start();
@@ -638,7 +638,7 @@ void QColumnViewPrivate::_q_clicked(const QModelIndex &index)
 {
     Q_Q(QColumnView);
     QModelIndex parent = index.parent();
-    QAbstractItemView *columnClicked = 0;
+    QAbstractItemView *columnClicked = nullptr;
     for (int column = 0; column < columns.count(); ++column) {
         if (columns.at(column)->rootIndex() == parent) {
             columnClicked = columns[column];
@@ -666,7 +666,7 @@ void QColumnViewPrivate::_q_clicked(const QModelIndex &index)
 QAbstractItemView *QColumnViewPrivate::createColumn(const QModelIndex &index, bool show)
 {
     Q_Q(QColumnView);
-    QAbstractItemView *view = 0;
+    QAbstractItemView *view = nullptr;
     if (model->hasChildren(index)) {
         view = q->createColumn(index);
         q->connect(view, SIGNAL(clicked(QModelIndex)),
@@ -1045,8 +1045,8 @@ QColumnViewPrivate::QColumnViewPrivate()
 :  QAbstractItemViewPrivate()
 ,showResizeGrips(true)
 ,offset(0)
-,previewWidget(0)
-,previewColumn(0)
+,previewWidget(nullptr)
+,previewColumn(nullptr)
 {
 }
 
diff --git a/src/widgets/itemviews/qdatawidgetmapper.cpp b/src/widgets/itemviews/qdatawidgetmapper.cpp
index 125ee73194..24039c42f6 100644
--- a/src/widgets/itemviews/qdatawidgetmapper.cpp
+++ b/src/widgets/itemviews/qdatawidgetmapper.cpp
@@ -56,7 +56,7 @@ public:
     Q_DECLARE_PUBLIC(QDataWidgetMapper)
 
     QDataWidgetMapperPrivate()
-        : model(QAbstractItemModelPrivate::staticEmptyModel()), delegate(0),
+        : model(QAbstractItemModelPrivate::staticEmptyModel()), delegate(nullptr),
           orientation(Qt::Horizontal), submitPolicy(QDataWidgetMapper::AutoSubmit)
     {
     }
@@ -226,7 +226,7 @@ void QDataWidgetMapperPrivate::_q_modelDestroyed()
 {
     Q_Q(QDataWidgetMapper);
 
-    model = 0;
+    model = nullptr;
     q->setModel(QAbstractItemModelPrivate::staticEmptyModel());
 }
 
@@ -374,7 +374,7 @@ QAbstractItemModel *QDataWidgetMapper::model() const
 {
     Q_D(const QDataWidgetMapper);
     return d->model == QAbstractItemModelPrivate::staticEmptyModel()
-            ? static_cast<QAbstractItemModel *>(0)
+            ? static_cast<QAbstractItemModel *>(nullptr)
             : d->model;
 }
 
@@ -567,7 +567,7 @@ QWidget *QDataWidgetMapper::mappedWidgetAt(int section) const
             return e.widget;
     }
 
-    return 0;
+    return nullptr;
 }
 
 /*!
diff --git a/src/widgets/itemviews/qdirmodel.cpp b/src/widgets/itemviews/qdirmodel.cpp
index c9e7c7b7a6..0d387d7def 100644
--- a/src/widgets/itemviews/qdirmodel.cpp
+++ b/src/widgets/itemviews/qdirmodel.cpp
@@ -75,7 +75,7 @@ class QDirModelPrivate : public QAbstractItemModelPrivate
 public:
     struct QDirNode
     {
-        QDirNode() : parent(0), populated(false), stat(false) {}
+        QDirNode() : parent(nullptr), populated(false), stat(false) {}
         QDirNode *parent;
         QFileInfo info;
         QIcon icon; // cache the icon
@@ -238,7 +238,7 @@ QDirModel::QDirModel(const QStringList &nameFilters,
     d->nameFilters = nameFilters.isEmpty() ? QStringList(QLatin1String("*")) : nameFilters;
     d->filters = filters;
     d->sort = sort;
-    d->root.parent = 0;
+    d->root.parent = nullptr;
     d->root.info = QFileInfo();
     d->clear(&d->root);
 }
@@ -293,7 +293,7 @@ QModelIndex QDirModel::index(int row, int column, const QModelIndex &parent) con
     if (row >= p->children.count())
         return QModelIndex();
     // now get the internal pointer for the index
-    QDirModelPrivate::QDirNode *n = d->node(row, d->indexValid(parent) ? p : 0);
+    QDirModelPrivate::QDirNode *n = d->node(row, d->indexValid(parent) ? p : nullptr);
     Q_ASSERT(n);
 
     return createIndex(row, column, n);
@@ -310,8 +310,8 @@ QModelIndex QDirModel::parent(const QModelIndex &child) const
     if (!d->indexValid(child))
         return QModelIndex();
     QDirModelPrivate::QDirNode *node = d->node(child);
-    QDirModelPrivate::QDirNode *par = (node ? node->parent : 0);
-    if (par == 0) // parent is the root node
+    QDirModelPrivate::QDirNode *par = (node ? node->parent : nullptr);
+    if (par == nullptr) // parent is the root node
         return QModelIndex();
 
     // get the parent's row
@@ -1159,7 +1159,7 @@ void QDirModelPrivate::init()
     filters = QDir::AllEntries | QDir::NoDotAndDotDot;
     sort = QDir::Name;
     nameFilters << QLatin1String("*");
-    root.parent = 0;
+    root.parent = nullptr;
     root.info = QFileInfo();
     clear(&root);
     roleNames.insert(QDirModel::FileIconRole, QByteArrayLiteral("fileIcon")); // == Qt::decoration
@@ -1170,7 +1170,7 @@ void QDirModelPrivate::init()
 QDirModelPrivate::QDirNode *QDirModelPrivate::node(int row, QDirNode *parent) const
 {
     if (row < 0)
-        return 0;
+        return nullptr;
 
     bool isDir = !parent || parent->info.isDir();
     QDirNode *p = (parent ? parent : &root);
@@ -1179,7 +1179,7 @@ QDirModelPrivate::QDirNode *QDirModelPrivate::node(int row, QDirNode *parent) co
 
     if (Q_UNLIKELY(row >= p->children.count())) {
         qWarning("node: the row does not exist");
-        return 0;
+        return nullptr;
     }
 
     return const_cast<QDirNode*>(&p->children.at(row));
@@ -1190,7 +1190,7 @@ QVector<QDirModelPrivate::QDirNode> QDirModelPrivate::children(QDirNode *parent,
     Q_ASSERT(parent);
     QFileInfoList infoList;
     if (parent == &root) {
-        parent = 0;
+        parent = nullptr;
         infoList = QDir::drives();
     } else if (parent->info.isDir()) {
         //resolve directory links only if requested.
@@ -1333,7 +1333,7 @@ void QDirModelPrivate::appendChild(QDirModelPrivate::QDirNode *parent, const QSt
     QDirModelPrivate::QDirNode node;
     node.populated = false;
     node.stat = shouldStat;
-    node.parent = (parent == &root ? 0 : parent);
+    node.parent = (parent == &root ? nullptr : parent);
     node.info = QFileInfo(path);
     node.info.setCaching(true);
 
diff --git a/src/widgets/itemviews/qheaderview.cpp b/src/widgets/itemviews/qheaderview.cpp
index d7bdf6aa4c..790f305463 100644
--- a/src/widgets/itemviews/qheaderview.cpp
+++ b/src/widgets/itemviews/qheaderview.cpp
@@ -1583,7 +1583,7 @@ int QHeaderView::minimumSectionSize() const
     Q_D(const QHeaderView);
     if (d->minimumSectionSize == -1) {
         QSize strut = QApplication::globalStrut();
-        int margin = 2 * style()->pixelMetric(QStyle::PM_HeaderMargin, 0, this);
+        int margin = 2 * style()->pixelMetric(QStyle::PM_HeaderMargin, nullptr, this);
         if (d->orientation == Qt::Horizontal)
             return qMax(strut.width(), (fontMetrics().maxWidth() + margin));
         return qMax(strut.height(), (fontMetrics().height() + margin));
@@ -2883,12 +2883,12 @@ void QHeaderView::paintSection(QPainter *painter, const QRect &rect, int logical
     opt.text = d->model->headerData(logicalIndex, d->orientation,
                                     Qt::DisplayRole).toString();
 
-    int margin = 2 * style()->pixelMetric(QStyle::PM_HeaderMargin, 0, this);
+    int margin = 2 * style()->pixelMetric(QStyle::PM_HeaderMargin, nullptr, this);
 
-    const Qt::Alignment headerArrowAlignment = static_cast<Qt::Alignment>(style()->styleHint(QStyle::SH_Header_ArrowAlignment, 0, this));
+    const Qt::Alignment headerArrowAlignment = static_cast<Qt::Alignment>(style()->styleHint(QStyle::SH_Header_ArrowAlignment, nullptr, this));
     const bool isHeaderArrowOnTheSide = headerArrowAlignment & Qt::AlignVCenter;
     if (isSortIndicatorShown() && sortIndicatorSection() == logicalIndex && isHeaderArrowOnTheSide)
-        margin += style()->pixelMetric(QStyle::PM_HeaderMarkSize, 0, this);
+        margin += style()->pixelMetric(QStyle::PM_HeaderMarkSize, nullptr, this);
 
     const QVariant variant = d->model->headerData(logicalIndex, d->orientation,
                                                   Qt::DecorationRole);
@@ -2896,8 +2896,8 @@ void QHeaderView::paintSection(QPainter *painter, const QRect &rect, int logical
     if (opt.icon.isNull())
         opt.icon = qvariant_cast<QPixmap>(variant);
     if (!opt.icon.isNull()) // see CT_HeaderSection
-        margin += style()->pixelMetric(QStyle::PM_SmallIconSize, 0, this) +
-                  style()->pixelMetric(QStyle::PM_HeaderMargin, 0, this);
+        margin += style()->pixelMetric(QStyle::PM_SmallIconSize, nullptr, this) +
+                  style()->pixelMetric(QStyle::PM_HeaderMargin, nullptr, this);
 
     if (d->textElideMode != Qt::ElideNone) {
         const QRect textRect = style()->subElementRect(QStyle::SE_HeaderLabel, &opt, this);
@@ -3275,7 +3275,7 @@ int QHeaderViewPrivate::sectionHandleAt(int position)
         return -1;
     int log = logicalIndex(visual);
     int pos = q->sectionViewportPosition(log);
-    int grip = q->style()->pixelMetric(QStyle::PM_HeaderGripMargin, 0, q);
+    int grip = q->style()->pixelMetric(QStyle::PM_HeaderGripMargin, nullptr, q);
 
     bool atLeft = position < pos + grip;
     bool atRight = (position > pos + q->sectionSize(log) - grip);
@@ -3814,10 +3814,10 @@ void QHeaderViewPrivate::updateDefaultSectionSizeFromStyle()
 {
     Q_Q(QHeaderView);
     if (orientation == Qt::Horizontal) {
-        defaultSectionSize = q->style()->pixelMetric(QStyle::PM_HeaderDefaultSectionSizeHorizontal, 0, q);
+        defaultSectionSize = q->style()->pixelMetric(QStyle::PM_HeaderDefaultSectionSizeHorizontal, nullptr, q);
     } else {
         defaultSectionSize = qMax(q->minimumSectionSize(),
-                                  q->style()->pixelMetric(QStyle::PM_HeaderDefaultSectionSizeVertical, 0, q));
+                                  q->style()->pixelMetric(QStyle::PM_HeaderDefaultSectionSizeVertical, nullptr, q));
     }
 }
 
diff --git a/src/widgets/itemviews/qitemdelegate.cpp b/src/widgets/itemviews/qitemdelegate.cpp
index 460764f1b8..daea907963 100644
--- a/src/widgets/itemviews/qitemdelegate.cpp
+++ b/src/widgets/itemviews/qitemdelegate.cpp
@@ -77,7 +77,7 @@ class QItemDelegatePrivate : public QAbstractItemDelegatePrivate
     Q_DECLARE_PUBLIC(QItemDelegate)
 
 public:
-    QItemDelegatePrivate() : f(0), clipPainting(true) {}
+    QItemDelegatePrivate() : f(nullptr), clipPainting(true) {}
 
     inline const QItemEditorFactory *editorFactory() const
         { return f ? f : QItemEditorFactory::defaultFactory(); }
@@ -149,7 +149,7 @@ QRect QItemDelegatePrivate::textLayoutBounds(const QStyleOptionViewItem &option,
     QStyle *style = w ? w->style() : QApplication::style();
     const bool wrapText = option.features & QStyleOptionViewItem::WrapText;
     // see QItemDelegate::drawDisplay
-    const int textMargin = style->pixelMetric(QStyle::PM_FocusFrameHMargin, 0, w) + 1;
+    const int textMargin = style->pixelMetric(QStyle::PM_FocusFrameHMargin, nullptr, w) + 1;
     switch (option.decorationPosition) {
     case QStyleOptionViewItem::Left:
     case QStyleOptionViewItem::Right:
@@ -502,9 +502,9 @@ QWidget *QItemDelegate::createEditor(QWidget *parent,
 {
     Q_D(const QItemDelegate);
     if (!index.isValid())
-        return 0;
+        return nullptr;
     const QItemEditorFactory *factory = d->f;
-    if (factory == 0)
+    if (factory == nullptr)
         factory = QItemEditorFactory::defaultFactory();
     QWidget *w = factory->createEditor(index.data(Qt::EditRole).userType(), parent);
     if (w)
@@ -533,7 +533,7 @@ void QItemDelegate::setEditorData(QWidget *editor, const QModelIndex &index) con
 
     if (!n.isEmpty()) {
         if (!v.isValid())
-            v = QVariant(editor->property(n).userType(), (const void *)0);
+            v = QVariant(editor->property(n).userType(), (const void *)nullptr);
         editor->setProperty(n, v);
     }
 #endif
@@ -586,7 +586,7 @@ void QItemDelegate::updateEditorGeometry(QWidget *editor,
     QPixmap pixmap = decoration(option, index.data(Qt::DecorationRole));
     QString text = QItemDelegatePrivate::replaceNewLine(index.data(Qt::DisplayRole).toString());
     QRect pixmapRect = QRect(QPoint(0, 0), option.decorationSize).intersected(pixmap.rect());
-    QRect textRect = textRectangle(0, option.rect, option.font, text);
+    QRect textRect = textRectangle(nullptr, option.rect, option.font, text);
     QRect checkRect = doCheck(option, textRect, index.data(Qt::CheckStateRole));
     QStyleOptionViewItem opt = option;
     opt.showDecorationSelected = true; // let the editor take up all available space
@@ -654,7 +654,7 @@ void QItemDelegate::drawDisplay(QPainter *painter, const QStyleOptionViewItem &o
 
     const QWidget *widget = d->widget(option);
     QStyle *style = widget ? widget->style() : QApplication::style();
-    const int textMargin = style->pixelMetric(QStyle::PM_FocusFrameHMargin, 0, widget) + 1;
+    const int textMargin = style->pixelMetric(QStyle::PM_FocusFrameHMargin, nullptr, widget) + 1;
     QRect textRect = rect.adjusted(textMargin, 0, -textMargin, 0); // remove width padding
     const bool wrapText = opt.features & QStyleOptionViewItem::WrapText;
     d->textOption.setWrapMode(wrapText ? QTextOption::WordWrap : QTextOption::ManualWrap);
@@ -841,7 +841,7 @@ void QItemDelegate::doLayout(const QStyleOptionViewItem &option,
     const bool hasText = textRect->isValid();
     const bool hasMargin = (hasText | hasPixmap | hasCheck);
     const int frameHMargin = hasMargin ?
-                style->pixelMetric(QStyle::PM_FocusFrameHMargin, 0, widget) + 1 : 0;
+                style->pixelMetric(QStyle::PM_FocusFrameHMargin, nullptr, widget) + 1 : 0;
     const int textMargin = hasText ? frameHMargin : 0;
     const int pixmapMargin = hasPixmap ? frameHMargin : 0;
     const int checkMargin = hasCheck ? frameHMargin : 0;
@@ -1242,7 +1242,7 @@ QStyleOptionViewItem QItemDelegate::setOptions(const QModelIndex &index,
         opt.palette.setBrush(QPalette::Text, qvariant_cast<QBrush>(value));
 
     // disable style animations for checkboxes etc. within itemviews (QTBUG-30146)
-    opt.styleObject = 0;
+    opt.styleObject = nullptr;
 
     return opt;
 }
diff --git a/src/widgets/itemviews/qitemeditorfactory.cpp b/src/widgets/itemviews/qitemeditorfactory.cpp
index 8ed2ee5f28..f874597d59 100644
--- a/src/widgets/itemviews/qitemeditorfactory.cpp
+++ b/src/widgets/itemviews/qitemeditorfactory.cpp
@@ -91,7 +91,7 @@ class QUIntSpinBox : public QSpinBox
     Q_OBJECT
     Q_PROPERTY(uint value READ uintValue WRITE setUIntValue NOTIFY uintValueChanged USER true)
 public:
-    explicit QUIntSpinBox(QWidget *parent = 0)
+    explicit QUIntSpinBox(QWidget *parent = nullptr)
       : QSpinBox(parent)
     {
         connect(this, SIGNAL(valueChanged(int)), SIGNAL(uintValueChanged()));
@@ -176,7 +176,7 @@ QWidget *QItemEditorFactory::createEditor(int userType, QWidget *parent) const
     QItemEditorCreatorBase *creator = creatorMap.value(userType, 0);
     if (!creator) {
         const QItemEditorFactory *dfactory = defaultFactory();
-        return dfactory == this ? 0 : dfactory->createEditor(userType, parent);
+        return dfactory == this ? nullptr : dfactory->createEditor(userType, parent);
     }
     return creator->createWidget(parent);
 }
@@ -295,8 +295,8 @@ QWidget *QDefaultItemEditorFactory::createEditor(int userType, QWidget *parent)
     default: {
         // the default editor is a lineedit
         QExpandingLineEdit *le = new QExpandingLineEdit(parent);
-        le->setFrame(le->style()->styleHint(QStyle::SH_ItemView_DrawDelegateFrame, 0, le));
-        if (!le->style()->styleHint(QStyle::SH_ItemView_ShowDecorationSelected, 0, le))
+        le->setFrame(le->style()->styleHint(QStyle::SH_ItemView_DrawDelegateFrame, nullptr, le));
+        if (!le->style()->styleHint(QStyle::SH_ItemView_ShowDecorationSelected, nullptr, le))
             le->setWidgetOwnsGeometry(true);
         return le; }
 #else
@@ -304,7 +304,7 @@ QWidget *QDefaultItemEditorFactory::createEditor(int userType, QWidget *parent)
         break;
 #endif
     }
-    return 0;
+    return nullptr;
 }
 
 QByteArray QDefaultItemEditorFactory::valuePropertyName(int userType) const
@@ -335,11 +335,11 @@ QByteArray QDefaultItemEditorFactory::valuePropertyName(int userType) const
     }
 }
 
-static QItemEditorFactory *q_default_factory = 0;
+static QItemEditorFactory *q_default_factory = nullptr;
 struct QDefaultFactoryCleaner
 {
     inline QDefaultFactoryCleaner() {}
-    ~QDefaultFactoryCleaner() { delete q_default_factory; q_default_factory = 0; }
+    ~QDefaultFactoryCleaner() { delete q_default_factory; q_default_factory = nullptr; }
 };
 
 /*!
diff --git a/src/widgets/itemviews/qlistview.cpp b/src/widgets/itemviews/qlistview.cpp
index 04cddf2926..de32082b5a 100644
--- a/src/widgets/itemviews/qlistview.cpp
+++ b/src/widgets/itemviews/qlistview.cpp
@@ -933,8 +933,8 @@ QStyleOptionViewItem QListView::viewOptions() const
     QStyleOptionViewItem option = QAbstractItemView::viewOptions();
     if (!d->iconSize.isValid()) { // otherwise it was already set in abstractitemview
         int pm = (d->viewMode == QListView::ListMode
-                  ? style()->pixelMetric(QStyle::PM_ListViewIconSize, 0, this)
-                  : style()->pixelMetric(QStyle::PM_IconViewIconSize, 0, this));
+                  ? style()->pixelMetric(QStyle::PM_ListViewIconSize, nullptr, this)
+                  : style()->pixelMetric(QStyle::PM_IconViewIconSize, nullptr, this));
         option.decorationSize = QSize(pm, pm);
     }
     if (d->viewMode == QListView::IconMode) {
@@ -1688,7 +1688,7 @@ bool QListView::event(QEvent *e)
 
 QListViewPrivate::QListViewPrivate()
     : QAbstractItemViewPrivate(),
-      commonListView(0),
+      commonListView(nullptr),
       wrap(false),
       space(0),
       flow(QListView::TopToBottom),
@@ -1733,10 +1733,10 @@ void QListViewPrivate::prepareItemsLayout()
     // Qt::ScrollBarAlwaysOn but scrollbar extent must be deduced if policy
     // is Qt::ScrollBarAsNeeded
     int verticalMargin = vbarpolicy==Qt::ScrollBarAsNeeded
-        ? q->style()->pixelMetric(QStyle::PM_ScrollBarExtent, 0, vbar) + frameAroundContents
+        ? q->style()->pixelMetric(QStyle::PM_ScrollBarExtent, nullptr, vbar) + frameAroundContents
         : 0;
     int horizontalMargin =  hbarpolicy==Qt::ScrollBarAsNeeded
-        ? q->style()->pixelMetric(QStyle::PM_ScrollBarExtent, 0, hbar) + frameAroundContents
+        ? q->style()->pixelMetric(QStyle::PM_ScrollBarExtent, nullptr, hbar) + frameAroundContents
         : 0;
 
     layoutBounds.adjust(0, 0, -verticalMargin, -horizontalMargin);
@@ -3072,7 +3072,7 @@ void QIconModeViewBase::doDynamicLayout(const QListViewLayoutInfo &info)
         moved.resize(items.count());
 
     QRect rect(QPoint(), topLeft);
-    QListViewItem *item = 0;
+    QListViewItem *item = nullptr;
     for (int row = info.first; row <= info.last; ++row) {
         item = &items[row];
         if (isHidden(row)) {
@@ -3178,7 +3178,7 @@ QVector<QModelIndex> QIconModeViewBase::intersectingSet(const QRect &area) const
     QVector<QModelIndex> res;
     that->interSectingVector = &res;
     that->tree.climbTree(area, &QIconModeViewBase::addLeaf, data);
-    that->interSectingVector = 0;
+    that->interSectingVector = nullptr;
     return res;
 }
 
diff --git a/src/widgets/itemviews/qlistwidget.cpp b/src/widgets/itemviews/qlistwidget.cpp
index 1931360dbc..f71e0f2822 100644
--- a/src/widgets/itemviews/qlistwidget.cpp
+++ b/src/widgets/itemviews/qlistwidget.cpp
@@ -75,7 +75,7 @@ void QListModel::clear()
     for (int i = 0; i < items.count(); ++i) {
         if (items.at(i)) {
             items.at(i)->d->theid = -1;
-            items.at(i)->view = 0;
+            items.at(i)->view = nullptr;
             delete items.at(i);
         }
     }
@@ -96,7 +96,7 @@ void QListModel::remove(QListWidgetItem *item)
     Q_ASSERT(row != -1);
     beginRemoveRows(QModelIndex(), row, row);
     items.at(row)->d->theid = -1;
-    items.at(row)->view = 0;
+    items.at(row)->view = nullptr;
     items.removeAt(row);
     endRemoveRows();
 }
@@ -156,11 +156,11 @@ void QListModel::insert(int row, const QStringList &labels)
 QListWidgetItem *QListModel::take(int row)
 {
     if (row < 0 || row >= items.count())
-        return 0;
+        return nullptr;
 
     beginRemoveRows(QModelIndex(), row, row);
     items.at(row)->d->theid = -1;
-    items.at(row)->view = 0;
+    items.at(row)->view = nullptr;
     QListWidgetItem *item = items.takeAt(row);
     endRemoveRows();
     return item;
@@ -263,7 +263,7 @@ bool QListModel::insertRows(int row, int count, const QModelIndex &parent)
 
     beginInsertRows(QModelIndex(), row, row + count - 1);
     QListWidget *view = qobject_cast<QListWidget*>(QObject::parent());
-    QListWidgetItem *itm = 0;
+    QListWidgetItem *itm = nullptr;
 
     for (int r = row; r < row + count; ++r) {
         itm = new QListWidgetItem;
@@ -282,10 +282,10 @@ bool QListModel::removeRows(int row, int count, const QModelIndex &parent)
         return false;
 
     beginRemoveRows(QModelIndex(), row, row + count - 1);
-    QListWidgetItem *itm = 0;
+    QListWidgetItem *itm = nullptr;
     for (int r = row; r < row + count; ++r) {
         itm = items.takeAt(row);
-        itm->view = 0;
+        itm->view = nullptr;
         itm->d->theid = -1;
         delete itm;
     }
@@ -1220,7 +1220,7 @@ void QListWidgetPrivate::_q_emitCurrentItemChanged(const QModelIndex &current,
     //persistentCurrent is invalid if something changed the model in response
     //to the currentItemChanged signal emission and the item was removed
     if (!persistentCurrent.isValid()) {
-        currentItem = 0;
+        currentItem = nullptr;
     }
 
     emit q->currentTextChanged(currentItem ? currentItem->text() : QString());
@@ -1478,7 +1478,7 @@ QListWidgetItem *QListWidget::item(int row) const
 {
     Q_D(const QListWidget);
     if (row < 0 || row >= d->model->rowCount())
-        return 0;
+        return nullptr;
     return d->listModel()->at(row);
 }
 
@@ -1548,7 +1548,7 @@ QListWidgetItem *QListWidget::takeItem(int row)
 {
     Q_D(QListWidget);
     if (row < 0 || row >= d->model->rowCount())
-        return 0;
+        return nullptr;
     return d->listModel()->take(row);
 }
 
@@ -2064,7 +2064,7 @@ QListWidgetItem *QListWidget::itemFromIndex(const QModelIndex &index) const
     Q_D(const QListWidget);
     if (d->isIndexValid(index))
         return d->listModel()->at(index.row());
-    return 0;
+    return nullptr;
 }
 
 /*!
diff --git a/src/widgets/itemviews/qstyleditemdelegate.cpp b/src/widgets/itemviews/qstyleditemdelegate.cpp
index 702e290da3..f42af2ea00 100644
--- a/src/widgets/itemviews/qstyleditemdelegate.cpp
+++ b/src/widgets/itemviews/qstyleditemdelegate.cpp
@@ -83,7 +83,7 @@ class QStyledItemDelegatePrivate : public QAbstractItemDelegatePrivate
     Q_DECLARE_PUBLIC(QStyledItemDelegate)
 
 public:
-    QStyledItemDelegatePrivate() : factory(0) { }
+    QStyledItemDelegatePrivate() : factory(nullptr) { }
 
     static const QWidget *widget(const QStyleOptionViewItem &option)
     {
@@ -351,7 +351,7 @@ void QStyledItemDelegate::initStyleOption(QStyleOptionViewItem *option,
     option->backgroundBrush = qvariant_cast<QBrush>(index.data(Qt::BackgroundRole));
 
     // disable style animations for checkboxes etc. within itemviews (QTBUG-30146)
-    option->styleObject = 0;
+    option->styleObject = nullptr;
 }
 
 /*!
@@ -426,7 +426,7 @@ QWidget *QStyledItemDelegate::createEditor(QWidget *parent,
 {
     Q_D(const QStyledItemDelegate);
     if (!index.isValid())
-        return 0;
+        return nullptr;
     return d->editorFactory()->createEditor(index.data(Qt::EditRole).userType(), parent);
 }
 
@@ -450,7 +450,7 @@ void QStyledItemDelegate::setEditorData(QWidget *editor, const QModelIndex &inde
 
     if (!n.isEmpty()) {
         if (!v.isValid())
-            v = QVariant(editor->property(n).userType(), (const void *)0);
+            v = QVariant(editor->property(n).userType(), (const void *)nullptr);
         editor->setProperty(n, v);
     }
 #endif
@@ -507,7 +507,7 @@ void QStyledItemDelegate::updateEditorGeometry(QWidget *editor,
     //or it is in a QTableView
 #if QT_CONFIG(tableview) && QT_CONFIG(lineedit)
     if (qobject_cast<QExpandingLineEdit*>(editor) && !qobject_cast<const QTableView*>(widget))
-        opt.showDecorationSelected = editor->style()->styleHint(QStyle::SH_ItemView_ShowDecorationSelected, 0, editor);
+        opt.showDecorationSelected = editor->style()->styleHint(QStyle::SH_ItemView_ShowDecorationSelected, nullptr, editor);
     else
 #endif
         opt.showDecorationSelected = true;
diff --git a/src/widgets/itemviews/qtablewidget.cpp b/src/widgets/itemviews/qtablewidget.cpp
index 91860341ee..8f37ef4c3d 100644
--- a/src/widgets/itemviews/qtablewidget.cpp
+++ b/src/widgets/itemviews/qtablewidget.cpp
@@ -49,7 +49,7 @@ QT_BEGIN_NAMESPACE
 
 QTableModel::QTableModel(int rows, int columns, QTableWidget *parent)
     : QAbstractTableModel(parent),
-      prototype(0),
+      prototype(nullptr),
       tableItems(rows * columns, 0),
       verticalHeaderItems(rows, 0),
       horizontalHeaderItems(columns, 0)
@@ -104,18 +104,18 @@ bool QTableModel::removeRows(int row, int count, const QModelIndex &)
     beginRemoveRows(QModelIndex(), row, row + count - 1);
     int i = tableIndex(row, 0);
     int n = count * columnCount();
-    QTableWidgetItem *oldItem = 0;
+    QTableWidgetItem *oldItem = nullptr;
     for (int j = i; j < n + i; ++j) {
         oldItem = tableItems.at(j);
         if (oldItem)
-            oldItem->view = 0;
+            oldItem->view = nullptr;
         delete oldItem;
     }
     tableItems.remove(qMax(i, 0), n);
     for (int v = row; v < row + count; ++v) {
         oldItem = verticalHeaderItems.at(v);
         if (oldItem)
-            oldItem->view = 0;
+            oldItem->view = nullptr;
         delete oldItem;
     }
     verticalHeaderItems.remove(row, count);
@@ -129,13 +129,13 @@ bool QTableModel::removeColumns(int column, int count, const QModelIndex &)
         return false;
 
     beginRemoveColumns(QModelIndex(), column, column + count - 1);
-    QTableWidgetItem *oldItem = 0;
+    QTableWidgetItem *oldItem = nullptr;
     for (int row = rowCount() - 1; row >= 0; --row) {
         int i = tableIndex(row, column);
         for (int j = i; j < i + count; ++j) {
             oldItem = tableItems.at(j);
             if (oldItem)
-                oldItem->view = 0;
+                oldItem->view = nullptr;
             delete oldItem;
         }
         tableItems.remove(i, count);
@@ -143,7 +143,7 @@ bool QTableModel::removeColumns(int column, int count, const QModelIndex &)
     for (int h=column; h<column+count; ++h) {
         oldItem = horizontalHeaderItems.at(h);
         if (oldItem)
-            oldItem->view = 0;
+            oldItem->view = nullptr;
         delete oldItem;
     }
     horizontalHeaderItems.remove(column, count);
@@ -162,7 +162,7 @@ void QTableModel::setItem(int row, int column, QTableWidgetItem *item)
 
     // remove old
     if (oldItem)
-        oldItem->view = 0;
+        oldItem->view = nullptr;
     delete tableItems.at(i);
 
     QTableWidget *view = qobject_cast<QTableWidget*>(QObject::parent());
@@ -180,7 +180,7 @@ void QTableModel::setItem(int row, int column, QTableWidgetItem *item)
         if (row < colItems.count())
             colItems.remove(row);
         int sortedRow;
-        if (item == 0) {
+        if (item == nullptr) {
             // move to after all non-0 (sortable) items
             sortedRow = colItems.count();
         } else {
@@ -222,7 +222,7 @@ QTableWidgetItem *QTableModel::takeItem(int row, int column)
     long i = tableIndex(row, column);
     QTableWidgetItem *itm = tableItems.value(i);
     if (itm) {
-        itm->view = 0;
+        itm->view = nullptr;
         itm->d->id = -1;
         tableItems[i] = 0;
         const QModelIndex ind = index(row, column);
@@ -239,7 +239,7 @@ QTableWidgetItem *QTableModel::item(int row, int column) const
 QTableWidgetItem *QTableModel::item(const QModelIndex &index) const
 {
     if (!isValid(index))
-        return 0;
+        return nullptr;
     return tableItems.at(tableIndex(index.row(), index.column()));
 }
 
@@ -277,7 +277,7 @@ void QTableModel::setHorizontalHeaderItem(int section, QTableWidgetItem *item)
         return;
 
     if (oldItem)
-        oldItem->view = 0;
+        oldItem->view = nullptr;
     delete oldItem;
 
     QTableWidget *view = qobject_cast<QTableWidget*>(QObject::parent());
@@ -299,7 +299,7 @@ void QTableModel::setVerticalHeaderItem(int section, QTableWidgetItem *item)
         return;
 
     if (oldItem)
-        oldItem->view = 0;
+        oldItem->view = nullptr;
     delete oldItem;
 
     QTableWidget *view = qobject_cast<QTableWidget*>(QObject::parent());
@@ -315,10 +315,10 @@ void QTableModel::setVerticalHeaderItem(int section, QTableWidgetItem *item)
 QTableWidgetItem *QTableModel::takeHorizontalHeaderItem(int section)
 {
     if (section < 0 || section >= horizontalHeaderItems.count())
-        return 0;
+        return nullptr;
     QTableWidgetItem *itm = horizontalHeaderItems.at(section);
     if (itm) {
-        itm->view = 0;
+        itm->view = nullptr;
         itm->itemFlags &= ~ItemIsHeaderItem;
         horizontalHeaderItems[section] = 0;
     }
@@ -328,10 +328,10 @@ QTableWidgetItem *QTableModel::takeHorizontalHeaderItem(int section)
 QTableWidgetItem *QTableModel::takeVerticalHeaderItem(int section)
 {
     if (section < 0 || section >= verticalHeaderItems.count())
-        return 0;
+        return nullptr;
     QTableWidgetItem *itm = verticalHeaderItems.at(section);
     if (itm) {
-        itm->view = 0;
+        itm->view = nullptr;
         itm->itemFlags &= ~ItemIsHeaderItem;
         verticalHeaderItems[section] = 0;
     }
@@ -571,7 +571,7 @@ void QTableModel::ensureSorted(int column, Qt::SortOrder order,
     sorting.reserve(count);
     for (int row = start; row <= end; ++row) {
         QTableWidgetItem *itm = item(row, column);
-        if (itm == 0) {
+        if (itm == nullptr) {
             // no more sortable items (all 0-items are
             // at the end of the table when it is sorted)
             break;
@@ -649,7 +649,7 @@ QVector<QTableWidgetItem*> QTableModel::columnItems(int column) const
     items.reserve(rc);
     for (int row = 0; row < rc; ++row) {
         QTableWidgetItem *itm = item(row, column);
-        if (itm == 0) {
+        if (itm == nullptr) {
             // no more sortable items (all 0-items are
             // at the end of the table when it is sorted)
             break;
@@ -718,7 +718,7 @@ QVariant QTableModel::headerData(int section, Qt::Orientation orientation, int r
     if (section < 0)
         return QVariant();
 
-    QTableWidgetItem *itm = 0;
+    QTableWidgetItem *itm = nullptr;
     if (orientation == Qt::Horizontal && section < horizontalHeaderItems.count())
         itm = horizontalHeaderItems.at(section);
     else if (orientation == Qt::Vertical && section < verticalHeaderItems.count())
@@ -741,7 +741,7 @@ bool QTableModel::setHeaderData(int section, Qt::Orientation orientation,
        (orientation == Qt::Vertical && verticalHeaderItems.size() <= section))
     return false;
 
-    QTableWidgetItem *itm = 0;
+    QTableWidgetItem *itm = nullptr;
     if (orientation == Qt::Horizontal)
         itm = horizontalHeaderItems.at(section);
     else
@@ -764,14 +764,14 @@ void QTableModel::clear()
 {
     for (int j = 0; j < verticalHeaderItems.count(); ++j) {
         if (verticalHeaderItems.at(j)) {
-            verticalHeaderItems.at(j)->view = 0;
+            verticalHeaderItems.at(j)->view = nullptr;
             delete verticalHeaderItems.at(j);
             verticalHeaderItems[j] = 0;
         }
     }
     for (int k = 0; k < horizontalHeaderItems.count(); ++k) {
         if (horizontalHeaderItems.at(k)) {
-            horizontalHeaderItems.at(k)->view = 0;
+            horizontalHeaderItems.at(k)->view = nullptr;
             delete horizontalHeaderItems.at(k);
             horizontalHeaderItems[k] = 0;
         }
@@ -784,7 +784,7 @@ void QTableModel::clearContents()
     beginResetModel();
     for (int i = 0; i < tableItems.count(); ++i) {
         if (tableItems.at(i)) {
-            tableItems.at(i)->view = 0;
+            tableItems.at(i)->view = nullptr;
             delete tableItems.at(i);
             tableItems[i] = 0;
         }
@@ -853,7 +853,7 @@ QMimeData *QTableModel::mimeData(const QModelIndexList &indexes) const
     // cachedIndexes is a little hack to avoid copying from QModelIndexList to
     // QList<QTreeWidgetItem*> and back again in the view
     cachedIndexes = indexes;
-    QMimeData *mimeData = (view ? view->mimeData(items) : 0);
+    QMimeData *mimeData = (view ? view->mimeData(items) : nullptr);
     cachedIndexes.clear();
     return mimeData;
 }
@@ -2040,7 +2040,7 @@ QTableWidgetItem *QTableWidget::takeItem(int row, int column)
     Q_D(QTableWidget);
     QTableWidgetItem *item = d->tableModel()->takeItem(row, column);
     if (item)
-        item->view = 0;
+        item->view = nullptr;
     return item;
 }
 
@@ -2076,7 +2076,7 @@ QTableWidgetItem *QTableWidget::takeVerticalHeaderItem(int row)
     Q_D(QTableWidget);
     QTableWidgetItem *itm = d->tableModel()->takeVerticalHeaderItem(row);
     if (itm)
-        itm->view = 0;
+        itm->view = nullptr;
     return itm;
 }
 
@@ -2115,7 +2115,7 @@ QTableWidgetItem *QTableWidget::takeHorizontalHeaderItem(int column)
     Q_D(QTableWidget);
     QTableWidgetItem *itm = d->tableModel()->takeHorizontalHeaderItem(column);
     if (itm)
-        itm->view = 0;
+        itm->view = nullptr;
     return itm;
 }
 
@@ -2126,7 +2126,7 @@ void QTableWidget::setVerticalHeaderLabels(const QStringList &labels)
 {
     Q_D(QTableWidget);
     QTableModel *model = d->tableModel();
-    QTableWidgetItem *item = 0;
+    QTableWidgetItem *item = nullptr;
     for (int i = 0; i < model->rowCount() && i < labels.count(); ++i) {
         item = model->verticalHeaderItem(i);
         if (!item) {
@@ -2144,7 +2144,7 @@ void QTableWidget::setHorizontalHeaderLabels(const QStringList &labels)
 {
     Q_D(QTableWidget);
     QTableModel *model = d->tableModel();
-    QTableWidgetItem *item = 0;
+    QTableWidgetItem *item = nullptr;
     for (int i = 0; i < model->columnCount() && i < labels.count(); ++i) {
         item = model->horizontalHeaderItem(i);
         if (!item) {
diff --git a/src/widgets/itemviews/qtreeview.cpp b/src/widgets/itemviews/qtreeview.cpp
index 442369c2ec..9aba17be70 100644
--- a/src/widgets/itemviews/qtreeview.cpp
+++ b/src/widgets/itemviews/qtreeview.cpp
@@ -1517,7 +1517,7 @@ void QTreeView::drawTree(QPainter *painter, const QRegion &region) const
 /// ### move to QObject :)
 static inline bool ancestorOf(QObject *widget, QObject *other)
 {
-    for (QObject *parent = other; parent != 0; parent = parent->parent()) {
+    for (QObject *parent = other; parent != nullptr; parent = parent->parent()) {
         if (parent == widget)
             return true;
     }
@@ -1888,7 +1888,7 @@ void QTreeView::mousePressEvent(QMouseEvent *event)
 {
     Q_D(QTreeView);
     bool handled = false;
-    if (style()->styleHint(QStyle::SH_ListViewExpand_SelectMouseType, 0, this) == QEvent::MouseButtonPress)
+    if (style()->styleHint(QStyle::SH_ListViewExpand_SelectMouseType, nullptr, this) == QEvent::MouseButtonPress)
         handled = d->expandOrCollapseItemAtPos(event->pos());
     if (!handled && d->itemDecorationAt(event->pos()) == -1)
         QAbstractItemView::mousePressEvent(event);
@@ -1907,7 +1907,7 @@ void QTreeView::mouseReleaseEvent(QMouseEvent *event)
     } else {
         if (state() == QAbstractItemView::DragSelectingState || state() == QAbstractItemView::DraggingState)
             setState(QAbstractItemView::NoState);
-        if (style()->styleHint(QStyle::SH_ListViewExpand_SelectMouseType, 0, this) == QEvent::MouseButtonRelease)
+        if (style()->styleHint(QStyle::SH_ListViewExpand_SelectMouseType, nullptr, this) == QEvent::MouseButtonRelease)
             d->expandOrCollapseItemAtPos(event->pos());
     }
 }
@@ -1944,7 +1944,7 @@ void QTreeView::mouseDoubleClickEvent(QMouseEvent *event)
         if (edit(persistent, DoubleClicked, event) || state() != NoState)
             return; // the double click triggered editing
 
-        if (!style()->styleHint(QStyle::SH_ItemView_ActivateItemOnSingleClick, 0, this))
+        if (!style()->styleHint(QStyle::SH_ItemView_ActivateItemOnSingleClick, nullptr, this))
             emit activated(persistent);
 
         d->pressedIndex = QModelIndex();
@@ -2208,7 +2208,7 @@ QModelIndex QTreeView::moveCursor(CursorAction cursorAction, Qt::KeyboardModifie
             d->collapse(vi, true);
             d->moveCursorUpdatedView = true;
         } else {
-            bool descend = style()->styleHint(QStyle::SH_ItemView_ArrowKeysNavigateIntoChildren, 0, this);
+            bool descend = style()->styleHint(QStyle::SH_ItemView_ArrowKeysNavigateIntoChildren, nullptr, this);
             if (descend) {
                 QModelIndex par = current.parent();
                 if (par.isValid() && par != rootIndex())
@@ -2244,7 +2244,7 @@ QModelIndex QTreeView::moveCursor(CursorAction cursorAction, Qt::KeyboardModifie
             d->expand(vi, true);
             d->moveCursorUpdatedView = true;
         } else {
-            bool descend = style()->styleHint(QStyle::SH_ItemView_ArrowKeysNavigateIntoChildren, 0, this);
+            bool descend = style()->styleHint(QStyle::SH_ItemView_ArrowKeysNavigateIntoChildren, nullptr, this);
             if (descend) {
                 QModelIndex idx = d->modelIndex(d->below(vi));
                 if (idx.parent() == current)
@@ -3051,7 +3051,7 @@ void QTreeViewPrivate::initialize()
     header->setDefaultAlignment(Qt::AlignLeft|Qt::AlignVCenter);
     q->setHeader(header);
 #if QT_CONFIG(animation)
-    animationsEnabled = q->style()->styleHint(QStyle::SH_Widget_Animation_Duration, 0, q) > 0;
+    animationsEnabled = q->style()->styleHint(QStyle::SH_Widget_Animation_Duration, nullptr, q) > 0;
     QObject::connect(&animatedOperation, SIGNAL(finished()), q, SLOT(_q_endAnimatedOperation()));
 #endif // animation
 }
@@ -3344,7 +3344,7 @@ void QTreeViewPrivate::layout(int i, bool recursiveExpanding, bool afterIsUninit
     int hidden = 0;
     int last = 0;
     int children = 0;
-    QTreeViewItem *item = 0;
+    QTreeViewItem *item = nullptr;
     for (int j = first; j < first + count; ++j) {
         current = model->index(j - first, 0, parent);
         if (isRowHidden(current)) {
@@ -3955,7 +3955,7 @@ int QTreeViewPrivate::accessibleTree2Index(const QModelIndex &index) const
 void QTreeViewPrivate::updateIndentationFromStyle()
 {
     Q_Q(const QTreeView);
-    indent = q->style()->pixelMetric(QStyle::PM_TreeViewIndentation, 0, q);
+    indent = q->style()->pixelMetric(QStyle::PM_TreeViewIndentation, nullptr, q);
 }
 
 /*!
diff --git a/src/widgets/itemviews/qtreewidget.cpp b/src/widgets/itemviews/qtreewidget.cpp
index cce0773fec..ddb31523fd 100644
--- a/src/widgets/itemviews/qtreewidget.cpp
+++ b/src/widgets/itemviews/qtreewidget.cpp
@@ -144,7 +144,7 @@ QTreeModel::~QTreeModel()
     clear();
     headerItem->view = nullptr;
     delete headerItem;
-    rootItem->view = 0;
+    rootItem->view = nullptr;
     delete rootItem;
 }
 
@@ -160,8 +160,8 @@ void QTreeModel::clear()
     beginResetModel();
     for (int i = 0; i < rootItem->childCount(); ++i) {
         QTreeWidgetItem *item = rootItem->children.at(i);
-        item->par = 0;
-        item->view = 0;
+        item->par = nullptr;
+        item->view = nullptr;
         delete item;
     }
     rootItem->children.clear();
@@ -214,7 +214,7 @@ void QTreeModel::setColumnCount(int columns)
 QTreeWidgetItem *QTreeModel::item(const QModelIndex &index) const
 {
     if (!index.isValid())
-        return 0;
+        return nullptr;
     return static_cast<QTreeWidgetItem*>(index.internalPointer());
 }
 
@@ -515,9 +515,9 @@ bool QTreeModel::removeRows(int row, int count, const QModelIndex &parent) {
     for (int i = row + count - 1; i >= row; --i) {
         QTreeWidgetItem *child = itm ? itm->takeChild(i) : rootItem->children.takeAt(i);
         Q_ASSERT(child);
-        child->view = 0;
+        child->view = nullptr;
         delete child;
-        child = 0;
+        child = nullptr;
     }
     blocker.unblock();
 
@@ -1612,11 +1612,11 @@ QTreeWidgetItem::~QTreeWidgetItem()
         }
     } else if (model) {
         if (this == model->headerItem) {
-            model->headerItem = 0;
+            model->headerItem = nullptr;
         } else {
             int i = model->rootItem->children.indexOf(this);
             if (i >= 0) {
-                model->beginRemoveItems(0, i, 1);
+                model->beginRemoveItems(nullptr, i, 1);
                 // users _could_ do changes when connected to rowsAboutToBeRemoved,
                 // so we check again to make sure 'i' is valid
                 if (!model->rootItem->children.isEmpty() && model->rootItem->children.at(i) == this)
@@ -1630,9 +1630,9 @@ QTreeWidgetItem::~QTreeWidgetItem()
     for (int i = 0; i < children.count(); ++i) {
         QTreeWidgetItem *child = children.at(i);
         // make sure the child does not try to remove itself from our children list
-        child->par = 0;
+        child->par = nullptr;
         // make sure the child does not try to remove itself from the top level list
-        child->view = 0;
+        child->view = nullptr;
         delete child;
     }
 
@@ -1648,16 +1648,16 @@ QTreeWidgetItem::~QTreeWidgetItem()
 */
 QTreeWidgetItem *QTreeWidgetItem::clone() const
 {
-    QTreeWidgetItem *copy = 0;
+    QTreeWidgetItem *copy = nullptr;
 
     QStack<const QTreeWidgetItem*> stack;
     QStack<QTreeWidgetItem*> parentStack;
     stack.push(this);
     parentStack.push(0);
 
-    QTreeWidgetItem *root = 0;
-    const QTreeWidgetItem *item = 0;
-    QTreeWidgetItem *parent = 0;
+    QTreeWidgetItem *root = nullptr;
+    const QTreeWidgetItem *item = nullptr;
+    QTreeWidgetItem *parent = nullptr;
     while (!stack.isEmpty()) {
         // get current item, and copied parent
         item = stack.pop();
@@ -1992,8 +1992,8 @@ void QTreeWidgetItem::write(QDataStream &out) const
     \sa data(), flags()
 */
 QTreeWidgetItem::QTreeWidgetItem(const QTreeWidgetItem &other)
-    : rtti(Type), values(other.values), view(0),
-      d(new QTreeWidgetItemPrivate(this)), par(0),
+    : rtti(Type), values(other.values), view(nullptr),
+      d(new QTreeWidgetItemPrivate(this)), par(nullptr),
       itemFlags(other.itemFlags)
 {
     d->display = other.d->display;
@@ -2036,14 +2036,14 @@ void QTreeWidgetItem::addChild(QTreeWidgetItem *child)
 */
 void QTreeWidgetItem::insertChild(int index, QTreeWidgetItem *child)
 {
-    if (index < 0 || index > children.count() || child == 0 || child->view != 0 || child->par != 0)
+    if (index < 0 || index > children.count() || child == nullptr || child->view != nullptr || child->par != nullptr)
         return;
 
     if (QTreeModel *model = treeModel()) {
         const bool wasSkipSort = model->skipPendingSort;
         model->skipPendingSort = true;
         if (model->rootItem == this)
-            child->par = 0;
+            child->par = nullptr;
         else
             child->par = this;
         if (view->isSortingEnabled()) {
@@ -2103,12 +2103,12 @@ QTreeWidgetItem *QTreeWidgetItem::takeChild(int index)
         if (model) model->beginRemoveItems(this, index, 1);
         d->updateHiddenStatus(children.at(index), false);
         QTreeWidgetItem *item = children.takeAt(index);
-        item->par = 0;
+        item->par = nullptr;
         QStack<QTreeWidgetItem*> stack;
         stack.push(item);
         while (!stack.isEmpty()) {
             QTreeWidgetItem *i = stack.pop();
-            i->view = 0;
+            i->view = nullptr;
             for (int c = 0; c < i->children.count(); ++c)
                 stack.push(i->children.at(c));
         }
@@ -2116,7 +2116,7 @@ QTreeWidgetItem *QTreeWidgetItem::takeChild(int index)
         if (model) model->endRemoveRows();
         return item;
     }
-    return 0;
+    return nullptr;
 }
 
 /*!
@@ -2163,7 +2163,7 @@ void QTreeWidgetItem::insertChildren(int index, const QList<QTreeWidgetItem*> &c
                 stack.push(child);
         }
         if (model && (model->rootItem == this))
-            child->par = 0;
+            child->par = nullptr;
         else
             child->par = this;
     }
@@ -2206,12 +2206,12 @@ QList<QTreeWidgetItem*> QTreeWidgetItem::takeChildren()
         if (model) model->beginRemoveItems(this, 0, children.count());
         for (int n = 0; n < children.count(); ++n) {
             QTreeWidgetItem *item = children.at(n);
-            item->par = 0;
+            item->par = nullptr;
             QStack<QTreeWidgetItem*> stack;
             stack.push(item);
             while (!stack.isEmpty()) {
                 QTreeWidgetItem *i = stack.pop();
-                i->view = 0;
+                i->view = nullptr;
                 for (int c = 0; c < i->children.count(); ++c)
                     stack.push(i->children.at(c));
             }
@@ -3306,7 +3306,7 @@ QTreeWidgetItem *QTreeWidget::itemAbove(const QTreeWidgetItem *item) const
 {
     Q_D(const QTreeWidget);
     if (item == d->treeModel()->headerItem)
-        return 0;
+        return nullptr;
     const QModelIndex index = d->index(item);
     const QModelIndex above = indexAbove(index);
     return d->item(above);
@@ -3321,7 +3321,7 @@ QTreeWidgetItem *QTreeWidget::itemBelow(const QTreeWidgetItem *item) const
 {
     Q_D(const QTreeWidget);
     if (item == d->treeModel()->headerItem)
-        return 0;
+        return nullptr;
     const QModelIndex index = d->index(item);
     const QModelIndex below = indexBelow(index);
     return d->item(below);
@@ -3424,14 +3424,14 @@ QMimeData *QTreeWidget::mimeData(const QList<QTreeWidgetItem*> items) const
         for (const auto *item : items) {
             if (Q_UNLIKELY(!item)) {
                 qWarning("QTreeWidget::mimeData: Null-item passed");
-                return 0;
+                return nullptr;
             }
 
             for (int c = 0; c < item->values.count(); ++c) {
                 const QModelIndex index = indexFromItem(item, c);
                 if (Q_UNLIKELY(!index.isValid())) {
                     qWarning() << "QTreeWidget::mimeData: No index associated with item :" << item;
-                    return 0;
+                    return nullptr;
                 }
                 indexes << index;
             }
diff --git a/src/widgets/itemviews/qtreewidgetitemiterator.cpp b/src/widgets/itemviews/qtreewidgetitemiterator.cpp
index 14c19fcb9c..a24106d90e 100644
--- a/src/widgets/itemviews/qtreewidgetitemiterator.cpp
+++ b/src/widgets/itemviews/qtreewidgetitemiterator.cpp
@@ -90,7 +90,7 @@ QTreeWidgetItemIterator::QTreeWidgetItemIterator(const QTreeWidgetItemIterator &
 */
 
 QTreeWidgetItemIterator::QTreeWidgetItemIterator(QTreeWidget *widget, IteratorFlags flags)
-: current(0), flags(flags)
+: current(nullptr), flags(flags)
 {
     Q_ASSERT(widget);
     QTreeModel *model = qobject_cast<QTreeModel*>(widget->model());
@@ -266,7 +266,7 @@ bool QTreeWidgetItemIterator::matchesFlags(const QTreeWidgetItem *item) const
 QTreeWidgetItem* QTreeWidgetItemIteratorPrivate::nextSibling(const QTreeWidgetItem* item) const
 {
     Q_ASSERT(item);
-    QTreeWidgetItem *next = 0;
+    QTreeWidgetItem *next = nullptr;
     if (QTreeWidgetItem *par = item->parent()) {
         int i = par->indexOfChild(const_cast<QTreeWidgetItem*>(item));
         next = par->child(i + 1);
@@ -280,9 +280,9 @@ QTreeWidgetItem* QTreeWidgetItemIteratorPrivate::nextSibling(const QTreeWidgetIt
 
 QTreeWidgetItem *QTreeWidgetItemIteratorPrivate::next(const QTreeWidgetItem *current)
 {
-    if (!current) return 0;
+    if (!current) return nullptr;
 
-    QTreeWidgetItem *next = 0;
+    QTreeWidgetItem *next = nullptr;
     if (current->childCount()) {
         // walk the child
         m_parentIndex.push(m_currentIndex);
@@ -307,9 +307,9 @@ QTreeWidgetItem *QTreeWidgetItemIteratorPrivate::next(const QTreeWidgetItem *cur
 
 QTreeWidgetItem *QTreeWidgetItemIteratorPrivate::previous(const QTreeWidgetItem *current)
 {
-    if (!current) return 0;
+    if (!current) return nullptr;
 
-    QTreeWidgetItem *prev = 0;
+    QTreeWidgetItem *prev = nullptr;
     // walk the previous sibling
     QTreeWidgetItem *parent = current->parent();
     prev = parent ? parent->child(m_currentIndex - 1)
@@ -347,7 +347,7 @@ void QTreeWidgetItemIteratorPrivate::ensureValidIterator(const QTreeWidgetItem *
     // we need to adjust the iterator.
     if (nextItem == itemToBeRemoved) {
         QTreeWidgetItem *parent = nextItem;
-        nextItem = 0;
+        nextItem = nullptr;
         while (parent && !nextItem) {
             nextItem = nextSibling(parent);
             parent = parent->parent();
@@ -358,7 +358,7 @@ void QTreeWidgetItemIteratorPrivate::ensureValidIterator(const QTreeWidgetItem *
             if (!(q->matchesFlags(nextItem))) ++(*q);
         } else {
             // set it to null.
-            q->current = 0;
+            q->current = nullptr;
             m_parentIndex.clear();
             return;
         }
diff --git a/src/widgets/kernel/qaction.cpp b/src/widgets/kernel/qaction.cpp
index 19ad65692b..64b0d69f6d 100644
--- a/src/widgets/kernel/qaction.cpp
+++ b/src/widgets/kernel/qaction.cpp
@@ -658,7 +658,7 @@ void QAction::setMenu(QMenu *menu)
 {
     Q_D(QAction);
     if (d->menu)
-        d->menu->d_func()->setOverrideMenuAction(0); //we reset the default action of any previous menu
+        d->menu->d_func()->setOverrideMenuAction(nullptr); //we reset the default action of any previous menu
     d->menu = menu;
     if (menu)
         menu->d_func()->setOverrideMenuAction(this);
diff --git a/src/widgets/kernel/qactiongroup.cpp b/src/widgets/kernel/qactiongroup.cpp
index 1d9213de0c..5dc12c48a4 100644
--- a/src/widgets/kernel/qactiongroup.cpp
+++ b/src/widgets/kernel/qactiongroup.cpp
@@ -81,7 +81,7 @@ void QActionGroupPrivate::_q_actionChanged()
                 current = action;
             }
         } else if (action == current) {
-            current = 0;
+            current = nullptr;
         }
     }
 }
@@ -271,11 +271,11 @@ void QActionGroup::removeAction(QAction *action)
     Q_D(QActionGroup);
     if (d->actions.removeAll(action)) {
         if (action == d->current)
-            d->current = 0;
+            d->current = nullptr;
         QObject::disconnect(action, SIGNAL(triggered()), this, SLOT(_q_actionTriggered()));
         QObject::disconnect(action, SIGNAL(changed()), this, SLOT(_q_actionChanged()));
         QObject::disconnect(action, SIGNAL(hovered()), this, SLOT(_q_actionHovered()));
-        action->d_func()->group = 0;
+        action->d_func()->group = nullptr;
     }
 }
 
diff --git a/src/widgets/kernel/qapplication.cpp b/src/widgets/kernel/qapplication.cpp
index 6d4baacfef..57771b3e12 100644
--- a/src/widgets/kernel/qapplication.cpp
+++ b/src/widgets/kernel/qapplication.cpp
@@ -138,7 +138,7 @@ QT_BEGIN_NAMESPACE
 Q_CORE_EXPORT void qt_call_post_routines();
 Q_GUI_EXPORT bool qt_sendShortcutOverrideEvent(QObject *o, ulong timestamp, int k, Qt::KeyboardModifiers mods, const QString &text = QString(), bool autorep = false, ushort count = 1);
 
-QApplicationPrivate *QApplicationPrivate::self = 0;
+QApplicationPrivate *QApplicationPrivate::self = nullptr;
 
 static void initSystemPalette()
 {
@@ -158,7 +158,7 @@ static void initSystemPalette()
 static void clearSystemPalette()
 {
     delete QApplicationPrivate::sys_pal;
-    QApplicationPrivate::sys_pal = 0;
+    QApplicationPrivate::sys_pal = nullptr;
 }
 
 bool QApplicationPrivate::autoSipEnabled = true;
@@ -169,8 +169,8 @@ QApplicationPrivate::QApplicationPrivate(int &argc, char **argv, int flags)
     application_type = QApplicationPrivate::Gui;
 
 #ifndef QT_NO_GESTURES
-    gestureManager = 0;
-    gestureWidget = 0;
+    gestureManager = nullptr;
+    gestureWidget = nullptr;
 #endif // QT_NO_GESTURES
 
     if (!self)
@@ -180,7 +180,7 @@ QApplicationPrivate::QApplicationPrivate(int &argc, char **argv, int flags)
 QApplicationPrivate::~QApplicationPrivate()
 {
     if (self == this)
-        self = 0;
+        self = nullptr;
 }
 
 void QApplicationPrivate::createEventDispatcher()
@@ -357,7 +357,7 @@ QWidget *QApplication::topLevelAt(const QPoint &pos)
         if (const QWidgetWindow *widgetWindow = qobject_cast<const QWidgetWindow *>(window))
             return widgetWindow->widget();
     }
-    return 0;
+    return nullptr;
 }
 
 /*!
@@ -372,22 +372,22 @@ QWidget *QApplication::topLevelAt(const QPoint &pos)
 void qt_init_tooltip_palette();
 void qt_cleanup();
 
-QStyle *QApplicationPrivate::app_style = 0;        // default application style
+QStyle *QApplicationPrivate::app_style = nullptr;        // default application style
 #ifndef QT_NO_STYLE_STYLESHEET
 QString QApplicationPrivate::styleSheet;           // default application stylesheet
 #endif
-QPointer<QWidget> QApplicationPrivate::leaveAfterRelease = 0;
+QPointer<QWidget> QApplicationPrivate::leaveAfterRelease = nullptr;
 
-QPalette *QApplicationPrivate::sys_pal = 0;        // default system palette
-QPalette *QApplicationPrivate::set_pal = 0;        // default palette set by programmer
+QPalette *QApplicationPrivate::sys_pal = nullptr;        // default system palette
+QPalette *QApplicationPrivate::set_pal = nullptr;        // default palette set by programmer
 
-QFont *QApplicationPrivate::sys_font = 0;        // default system font
-QFont *QApplicationPrivate::set_font = 0;        // default font set by programmer
+QFont *QApplicationPrivate::sys_font = nullptr;        // default system font
+QFont *QApplicationPrivate::set_font = nullptr;        // default font set by programmer
 
-QWidget *QApplicationPrivate::main_widget = 0;        // main application widget
-QWidget *QApplicationPrivate::focus_widget = 0;        // has keyboard input focus
-QWidget *QApplicationPrivate::hidden_focus_widget = 0; // will get keyboard input focus after show()
-QWidget *QApplicationPrivate::active_window = 0;        // toplevel with keyboard focus
+QWidget *QApplicationPrivate::main_widget = nullptr;        // main application widget
+QWidget *QApplicationPrivate::focus_widget = nullptr;        // has keyboard input focus
+QWidget *QApplicationPrivate::hidden_focus_widget = nullptr; // will get keyboard input focus after show()
+QWidget *QApplicationPrivate::active_window = nullptr;        // toplevel with keyboard focus
 #if QT_CONFIG(wheelevent)
 QPointer<QWidget> QApplicationPrivate::wheel_widget;
 #endif
@@ -419,9 +419,9 @@ Q_GLOBAL_STATIC(FontHash, app_fonts)
 PaletteHash *qt_app_palettes_hash() { return app_palettes(); }
 FontHash *qt_app_fonts_hash() { return app_fonts(); }
 
-QWidgetList *QApplicationPrivate::popupWidgets = 0;        // has keyboard input focus
+QWidgetList *QApplicationPrivate::popupWidgets = nullptr;        // has keyboard input focus
 
-QDesktopWidget *qt_desktopWidget = 0;                // root window widgets
+QDesktopWidget *qt_desktopWidget = nullptr;                // root window widgets
 
 /*!
     \internal
@@ -434,7 +434,7 @@ void QApplicationPrivate::process_cmdline()
     if (!styleOverride.isEmpty()) {
         if (app_style) {
             delete app_style;
-            app_style = 0;
+            app_style = nullptr;
         }
     }
 
@@ -473,7 +473,7 @@ void QApplicationPrivate::process_cmdline()
     }
 
     if(j < argc) {
-        argv[j] = 0;
+        argv[j] = nullptr;
         argc = j;
     }
 }
@@ -620,7 +620,7 @@ void QApplicationPrivate::initialize()
 
 static void setPossiblePalette(const QPalette *palette, const char *className)
 {
-    if (palette == 0)
+    if (palette == nullptr)
         return;
     QApplicationPrivate::setPalette_helper(*palette, className, false);
 }
@@ -746,7 +746,7 @@ QWidget *QApplication::activePopupWidget()
 QWidget *QApplication::activeModalWidget()
 {
     QWidgetWindow *widgetWindow = qobject_cast<QWidgetWindow *>(modalWindow());
-    return widgetWindow ? widgetWindow->widget() : 0;
+    return widgetWindow ? widgetWindow->widget() : nullptr;
 }
 
 /*!
@@ -769,12 +769,12 @@ QApplication::~QApplication()
     QApplicationPrivate::is_app_running = false;
 
     delete QWidgetPrivate::mapper;
-    QWidgetPrivate::mapper = 0;
+    QWidgetPrivate::mapper = nullptr;
 
     // delete all widgets
     if (QWidgetPrivate::allWidgets) {
         QWidgetSet *mySet = QWidgetPrivate::allWidgets;
-        QWidgetPrivate::allWidgets = 0;
+        QWidgetPrivate::allWidgets = nullptr;
         for (QWidgetSet::ConstIterator it = mySet->constBegin(), cend = mySet->constEnd(); it != cend; ++it) {
             QWidget *w = *it;
             if (!w->parent())                        // window
@@ -784,23 +784,23 @@ QApplication::~QApplication()
     }
 
     delete qt_desktopWidget;
-    qt_desktopWidget = 0;
+    qt_desktopWidget = nullptr;
 
     delete QApplicationPrivate::app_pal;
-    QApplicationPrivate::app_pal = 0;
+    QApplicationPrivate::app_pal = nullptr;
     clearSystemPalette();
     delete QApplicationPrivate::set_pal;
-    QApplicationPrivate::set_pal = 0;
+    QApplicationPrivate::set_pal = nullptr;
     app_palettes()->clear();
 
     delete QApplicationPrivate::sys_font;
-    QApplicationPrivate::sys_font = 0;
+    QApplicationPrivate::sys_font = nullptr;
     delete QApplicationPrivate::set_font;
-    QApplicationPrivate::set_font = 0;
+    QApplicationPrivate::set_font = nullptr;
     app_fonts()->clear();
 
     delete QApplicationPrivate::app_style;
-    QApplicationPrivate::app_style = 0;
+    QApplicationPrivate::app_style = nullptr;
 
 #if QT_CONFIG(draganddrop)
     if (qt_is_gui_used)
@@ -846,7 +846,7 @@ void qt_cleanup()
     QPixmapCache::clear();
     QColormap::cleanup();
 
-    QApplicationPrivate::active_window = 0; //### this should not be necessary
+    QApplicationPrivate::active_window = nullptr; //### this should not be necessary
 #if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
 #if defined(Q_OS_WIN) && !defined(Q_OS_WINRT)
     if (displayDC) {
@@ -892,7 +892,7 @@ QWidget *QApplication::widgetAt(const QPoint &p)
         QRegion newmask = (oldmask.isEmpty() ? QRegion(window->rect()) : oldmask)
                           - QRegion(wpoint.x(), wpoint.y(), 1, 1);
         window->setMask(newmask);
-        QWidget *recurse = 0;
+        QWidget *recurse = nullptr;
         if (QApplication::topLevelAt(p) != window) // verify recursion will terminate
             recurse = widgetAt(x, y);
         if (oldmask.isEmpty())
@@ -925,7 +925,7 @@ bool QApplication::compressEvent(QEvent *event, QObject *receiver, QPostEventLis
           || event->type() == QEvent::LanguageChange)) {
         for (QPostEventList::const_iterator it = postedEvents->constBegin(); it != postedEvents->constEnd(); ++it) {
             const QPostEvent &cur = *it;
-            if (cur.receiver != receiver || cur.event == 0 || cur.event->type() != event->type())
+            if (cur.receiver != receiver || cur.event == nullptr || cur.event->type() != event->type())
                 continue;
             if (cur.event->type() == QEvent::LayoutRequest
                  || cur.event->type() == QEvent::UpdateRequest) {
@@ -1020,7 +1020,7 @@ QStyle *QApplication::style()
         return QApplicationPrivate::app_style;
     if (!qobject_cast<QApplication *>(QCoreApplication::instance())) {
         Q_ASSERT(!"No style available without QApplication!");
-        return 0;
+        return nullptr;
     }
 
     if (!QApplicationPrivate::app_style) {
@@ -1048,7 +1048,7 @@ QStyle *QApplication::style()
         }
         if (!app_style) {
             Q_ASSERT(!"No styles available!");
-            return 0;
+            return nullptr;
         }
     }
     // take ownership of the style
@@ -1202,7 +1202,7 @@ QStyle* QApplication::setStyle(const QString& style)
 {
     QStyle *s = QStyleFactory::create(style);
     if (!s)
-        return 0;
+        return nullptr;
 
     setStyle(s);
     return s;
@@ -1695,7 +1695,7 @@ void QApplicationPrivate::setFocusWidget(QWidget *focus, Qt::FocusReason reason)
         return;
 #endif
 
-    hidden_focus_widget = 0;
+    hidden_focus_widget = nullptr;
 
     if (focus != focus_widget) {
         if (focus && focus->isHidden()) {
@@ -1893,7 +1893,7 @@ bool QApplication::event(QEvent *e)
 #endif
     } else if (e->type() == QEvent::Timer) {
         QTimerEvent *te = static_cast<QTimerEvent*>(e);
-        Q_ASSERT(te != 0);
+        Q_ASSERT(te != nullptr);
         if (te->timerId() == d->toolTipWakeUp.timerId()) {
             d->toolTipWakeUp.stop();
             if (d->toolTipWidget) {
@@ -1905,14 +1905,14 @@ bool QApplication::event(QEvent *e)
                 while (w && !showToolTip) {
                     showToolTip = w->isActiveWindow();
                     w = w->parentWidget();
-                    w = w ? w->window() : 0;
+                    w = w ? w->window() : nullptr;
                 }
                 if (showToolTip) {
                     QHelpEvent e(QEvent::ToolTip, d->toolTipPos, d->toolTipGlobalPos);
                     QCoreApplication::sendEvent(d->toolTipWidget, &e);
                     if (e.isAccepted()) {
                         QStyle *s = d->toolTipWidget->style();
-                        int sleepDelay = s->styleHint(QStyle::SH_ToolTip_FallAsleepDelay, 0, d->toolTipWidget, 0);
+                        int sleepDelay = s->styleHint(QStyle::SH_ToolTip_FallAsleepDelay, nullptr, d->toolTipWidget, nullptr);
                         d->toolTipFallAsleep.start(sleepDelay, this);
                     }
                 }
@@ -1982,7 +1982,7 @@ void QApplicationPrivate::notifyLayoutDirectionChange()
 */
 void QApplication::setActiveWindow(QWidget* act)
 {
-    QWidget* window = act?act->window():0;
+    QWidget* window = act?act->window():nullptr;
 
     if (QApplicationPrivate::active_window == window)
         return;
@@ -1998,7 +1998,7 @@ void QApplication::setActiveWindow(QWidget* act)
     QWidgetList toBeDeactivated;
 
     if (QApplicationPrivate::active_window) {
-        if (style()->styleHint(QStyle::SH_Widget_ShareActivation, 0, QApplicationPrivate::active_window)) {
+        if (style()->styleHint(QStyle::SH_Widget_ShareActivation, nullptr, QApplicationPrivate::active_window)) {
             const QWidgetList list = topLevelWidgets();
             for (auto *w : list) {
                 if (w->isVisible() && w->isActiveWindow())
@@ -2020,7 +2020,7 @@ void QApplication::setActiveWindow(QWidget* act)
     QApplicationPrivate::active_window = window;
 
     if (QApplicationPrivate::active_window) {
-        if (style()->styleHint(QStyle::SH_Widget_ShareActivation, 0, QApplicationPrivate::active_window)) {
+        if (style()->styleHint(QStyle::SH_Widget_ShareActivation, nullptr, QApplicationPrivate::active_window)) {
             const QWidgetList list = topLevelWidgets();
             for (auto *w : list) {
                 if (w->isVisible() && w->isActiveWindow())
@@ -2049,10 +2049,10 @@ void QApplication::setActiveWindow(QWidget* act)
         sendSpontaneousEvent(w, &activationChange);
     }
 
-    if (QApplicationPrivate::popupWidgets == 0) { // !inPopupMode()
+    if (QApplicationPrivate::popupWidgets == nullptr) { // !inPopupMode()
         // then focus events
         if (!QApplicationPrivate::active_window && QApplicationPrivate::focus_widget) {
-            QApplicationPrivate::setFocusWidget(0, Qt::ActiveWindowFocusReason);
+            QApplicationPrivate::setFocusWidget(nullptr, Qt::ActiveWindowFocusReason);
         } else if (QApplicationPrivate::active_window) {
             QWidget *w = QApplicationPrivate::active_window->focusWidget();
             if (w && w->isVisible() /*&& w->focusPolicy() != QWidget::NoFocus*/)
@@ -2067,7 +2067,7 @@ void QApplication::setActiveWindow(QWidget* act)
                     if (!w && QApplicationPrivate::active_window->focusPolicy() != Qt::NoFocus)
                         QApplicationPrivate::setFocusWidget(QApplicationPrivate::active_window, Qt::ActiveWindowFocusReason);
                     else if (!QApplicationPrivate::active_window->isAncestorOf(w))
-                        QApplicationPrivate::setFocusWidget(0, Qt::ActiveWindowFocusReason);
+                        QApplicationPrivate::setFocusWidget(nullptr, Qt::ActiveWindowFocusReason);
                 }
             }
         }
@@ -2095,7 +2095,7 @@ QWidget *qt_tlw_for_window(QWindow *wnd)
                 return tlw;
         }
     }
-    return 0;
+    return nullptr;
 }
 
 void QApplicationPrivate::notifyActiveWindowChange(QWindow *previous)
@@ -2158,7 +2158,7 @@ QWidget *QApplicationPrivate::focusNextPrevChild_helper(QWidget *toplevel, bool
         test = test->d_func()->focus_next;
     }
 
-    if (wrappingOccurred != 0)
+    if (wrappingOccurred != nullptr)
         *wrappingOccurred = next ? focusWidgetAfterWindow : !focusWidgetAfterWindow;
 
     if (w == f) {
@@ -2166,7 +2166,7 @@ QWidget *QApplicationPrivate::focusNextPrevChild_helper(QWidget *toplevel, bool
             w->window()->setAttribute(Qt::WA_KeyboardFocusChange);
             w->update();
         }
-        return 0;
+        return nullptr;
     }
     return w;
 }
@@ -2248,7 +2248,7 @@ void QApplicationPrivate::dispatchEnterLeave(QWidget* enter, QWidget* leave, con
     QEvent leaveEvent(QEvent::Leave);
     for (int i = 0; i < leaveList.size(); ++i) {
         auto *w = leaveList.at(i);
-        if (!QApplication::activeModalWidget() || QApplicationPrivate::tryModalHelper(w, 0)) {
+        if (!QApplication::activeModalWidget() || QApplicationPrivate::tryModalHelper(w, nullptr)) {
             QCoreApplication::sendEvent(w, &leaveEvent);
             if (w->testAttribute(Qt::WA_Hover) &&
                 (!QApplication::activePopupWidget() || QApplication::activePopupWidget() == w->window())) {
@@ -2267,7 +2267,7 @@ void QApplicationPrivate::dispatchEnterLeave(QWidget* enter, QWidget* leave, con
         const QPoint windowPos = qAsConst(enterList).back()->window()->mapFromGlobal(globalPos);
         for (auto it = enterList.crbegin(), end = enterList.crend(); it != end; ++it) {
             auto *w = *it;
-            if (!QApplication::activeModalWidget() || QApplicationPrivate::tryModalHelper(w, 0)) {
+            if (!QApplication::activeModalWidget() || QApplicationPrivate::tryModalHelper(w, nullptr)) {
                 const QPointF localPos = w->mapFromGlobal(globalPos);
                 QEnterEvent enterEvent(localPos, windowPos, globalPosF);
                 QCoreApplication::sendEvent(w, &enterEvent);
@@ -2287,7 +2287,7 @@ void QApplicationPrivate::dispatchEnterLeave(QWidget* enter, QWidget* leave, con
     const bool enterOnAlien = (enter && (isAlien(enter) || enter->testAttribute(Qt::WA_DontShowOnScreen)));
     // Whenever we leave an alien widget on X11/QPA, we need to reset its nativeParentWidget()'s cursor.
     // This is not required on Windows as the cursor is reset on every single mouse move.
-    QWidget *parentOfLeavingCursor = 0;
+    QWidget *parentOfLeavingCursor = nullptr;
     for (int i = 0; i < leaveList.size(); ++i) {
         auto *w = leaveList.at(i);
         if (!isAlien(w))
@@ -2353,7 +2353,7 @@ bool QApplicationPrivate::isBlockedByModal(QWidget *widget)
 
 bool QApplicationPrivate::isWindowBlocked(QWindow *window, QWindow **blockingWindow) const
 {
-    QWindow *unused = 0;
+    QWindow *unused = nullptr;
     if (Q_UNLIKELY(!window)) {
         qWarning().nospace() << "window == 0 passed.";
         return false;
@@ -2362,13 +2362,13 @@ bool QApplicationPrivate::isWindowBlocked(QWindow *window, QWindow **blockingWin
         blockingWindow = &unused;
 
     if (modalWindowList.isEmpty()) {
-        *blockingWindow = 0;
+        *blockingWindow = nullptr;
         return false;
     }
     QWidget *popupWidget = QApplication::activePopupWidget();
-    QWindow *popupWindow = popupWidget ? popupWidget->windowHandle() : 0;
+    QWindow *popupWindow = popupWidget ? popupWidget->windowHandle() : nullptr;
     if (popupWindow == window || (!popupWindow && QWindowPrivate::get(window)->isPopup())) {
-        *blockingWindow = 0;
+        *blockingWindow = nullptr;
         return false;
     }
 
@@ -2378,7 +2378,7 @@ bool QApplicationPrivate::isWindowBlocked(QWindow *window, QWindow **blockingWin
         // A window is not blocked by another modal window if the two are
         // the same, or if the window is a child of the modal window.
         if (window == modalWindow || modalWindow->isAncestorOf(window, QWindow::IncludeTransients)) {
-            *blockingWindow = 0;
+            *blockingWindow = nullptr;
             return false;
         }
 
@@ -2389,7 +2389,7 @@ bool QApplicationPrivate::isWindowBlocked(QWindow *window, QWindow **blockingWin
             // modalWindow's widget, this normally happens when waiting for a
             // native dialog. use WindowModal if we are the child of a group
             // leader; otherwise use ApplicationModal.
-            QWidget *m = modalWidgetWindow ? modalWidgetWindow->widget() : 0;
+            QWidget *m = modalWidgetWindow ? modalWidgetWindow->widget() : nullptr;
             while (m && !m->testAttribute(Qt::WA_GroupLeader)) {
                 m = m->parentWidget();
                 if (m)
@@ -2404,13 +2404,13 @@ bool QApplicationPrivate::isWindowBlocked(QWindow *window, QWindow **blockingWin
         case Qt::ApplicationModal:
         {
             QWidgetWindow *widgetWindow = qobject_cast<QWidgetWindow *>(window);
-            QWidget *groupLeaderForWidget = widgetWindow ? widgetWindow->widget() : 0;
+            QWidget *groupLeaderForWidget = widgetWindow ? widgetWindow->widget() : nullptr;
             while (groupLeaderForWidget && !groupLeaderForWidget->testAttribute(Qt::WA_GroupLeader))
                 groupLeaderForWidget = groupLeaderForWidget->parentWidget();
 
             if (groupLeaderForWidget) {
                 // if \a widget has WA_GroupLeader, it can only be blocked by ApplicationModal children
-                QWidget *m = modalWidgetWindow ? modalWidgetWindow->widget() : 0;
+                QWidget *m = modalWidgetWindow ? modalWidgetWindow->widget() : nullptr;
                 while (m && m != groupLeaderForWidget && !m->testAttribute(Qt::WA_GroupLeader))
                     m = m->parentWidget();
                 if (m == groupLeaderForWidget) {
@@ -2450,7 +2450,7 @@ bool QApplicationPrivate::isWindowBlocked(QWindow *window, QWindow **blockingWin
             break;
         }
     }
-    *blockingWindow = 0;
+    *blockingWindow = nullptr;
     return false;
 }
 
@@ -2474,7 +2474,7 @@ bool QApplicationPrivate::tryModalHelper(QWidget *widget, QWidget **rettop)
 
 bool qt_try_modal(QWidget *widget, QEvent::Type type)
 {
-    QWidget * top = 0;
+    QWidget * top = nullptr;
 
     if (QApplicationPrivate::tryModalHelper(widget, &top))
         return true;
@@ -2499,7 +2499,7 @@ bool qt_try_modal(QWidget *widget, QEvent::Type type)
         break;
     }
 
-    if (block_event && top && top->parentWidget() == 0)
+    if (block_event && top && top->parentWidget() == nullptr)
         top->raise();
 
     return !block_event;
@@ -2523,11 +2523,11 @@ QWidget *QApplicationPrivate::pickMouseReceiver(QWidget *candidate, const QPoint
     QWidget *mouseGrabber = QWidget::mouseGrabber();
     if (((type == QEvent::MouseMove && buttons) || (type == QEvent::MouseButtonRelease))
             && !buttonDown && !mouseGrabber) {
-        return 0;
+        return nullptr;
     }
 
     if (alienWidget && alienWidget->internalWinId())
-        alienWidget = 0;
+        alienWidget = nullptr;
 
     QWidget *receiver = candidate;
 
@@ -2560,7 +2560,7 @@ bool QApplicationPrivate::sendMouseEvent(QWidget *receiver, QMouseEvent *event,
     Q_ASSERT(buttonDown);
 
     if (alienWidget && !isAlien(alienWidget))
-        alienWidget = 0;
+        alienWidget = nullptr;
 
     QPointer<QWidget> receiverGuard = receiver;
     QPointer<QWidget> nativeGuard = nativeWidget;
@@ -2575,7 +2575,7 @@ bool QApplicationPrivate::sendMouseEvent(QWidget *receiver, QMouseEvent *event,
     // leaveAfterRelease has not been updated.
     // This happens e.g. when modal dialog or popup is shown as a response to button click.
     if (leaveAfterRelease && !*buttonDown && !event->buttons())
-        leaveAfterRelease = 0;
+        leaveAfterRelease = nullptr;
 
     if (*buttonDown) {
         if (!graphicsWidget) {
@@ -2584,7 +2584,7 @@ bool QApplicationPrivate::sendMouseEvent(QWidget *receiver, QMouseEvent *event,
             if ((alienWidget || !receiver->internalWinId()) && !leaveAfterRelease && !QWidget::mouseGrabber())
                 leaveAfterRelease = *buttonDown;
             if (event->type() == QEvent::MouseButtonRelease && !event->buttons())
-                *buttonDown = 0;
+                *buttonDown = nullptr;
         }
     } else if (lastMouseReceiver && widgetUnderMouse) {
         // Dispatch enter/leave if we move:
@@ -2612,7 +2612,7 @@ bool QApplicationPrivate::sendMouseEvent(QWidget *receiver, QMouseEvent *event,
 
     // We need this quard in case someone opens a modal dialog / popup. If that's the case
     // leaveAfterRelease is set to null, but we shall not update lastMouseReceiver.
-    const bool wasLeaveAfterRelease = leaveAfterRelease != 0;
+    const bool wasLeaveAfterRelease = leaveAfterRelease != nullptr;
     bool result = true;
     // This code is used for sending the synthetic enter/leave events for cases where it is needed
     // due to other events causing the widget under the mouse to change. However in those cases
@@ -2630,18 +2630,18 @@ bool QApplicationPrivate::sendMouseEvent(QWidget *receiver, QMouseEvent *event,
         // Dispatch enter/leave if:
         // 1) the mouse grabber is an alien widget
         // 2) the button is released on an alien widget
-        QWidget *enter = 0;
+        QWidget *enter = nullptr;
         if (nativeGuard)
             enter = alienGuard ? alienWidget : nativeWidget;
         else // The receiver is typically deleted on mouse release with drag'n'drop.
             enter = QApplication::widgetAt(event->globalPos());
         dispatchEnterLeave(enter, leaveAfterRelease, event->screenPos());
-        leaveAfterRelease = 0;
+        leaveAfterRelease = nullptr;
         lastMouseReceiver = enter;
     } else if (!wasLeaveAfterRelease) {
         if (activePopupWidget) {
             if (!QWidget::mouseGrabber())
-                lastMouseReceiver = alienGuard ? alienWidget : (nativeGuard ? nativeWidget : 0);
+                lastMouseReceiver = alienGuard ? alienWidget : (nativeGuard ? nativeWidget : nullptr);
         } else {
             lastMouseReceiver = receiverGuard ? receiver : QApplication::widgetAt(event->globalPos());
         }
@@ -2696,7 +2696,7 @@ void QApplicationPrivate::sendSyntheticEnterLeave(QWidget *widget)
         return; // Mouse cursor not inside the widget or any of its children.
 
     if (widget->data->in_destructor && qt_button_down == widget)
-        qt_button_down = 0;
+        qt_button_down = nullptr;
 
     // A mouse move is not actually sent, but we utilize the sendMouseEvent() call to send the
     // enter/leave events as appropriate
@@ -3048,9 +3048,9 @@ bool QApplication::notify(QObject *receiver, QEvent *e)
                     key->accept();
                 else
                     key->ignore();
-                QWidget *w = isWidget ? static_cast<QWidget *>(receiver) : 0;
+                QWidget *w = isWidget ? static_cast<QWidget *>(receiver) : nullptr;
 #if QT_CONFIG(graphicsview)
-                QGraphicsWidget *gw = isGraphicsWidget ? static_cast<QGraphicsWidget *>(receiver) : 0;
+                QGraphicsWidget *gw = isGraphicsWidget ? static_cast<QGraphicsWidget *>(receiver) : nullptr;
 #endif
                 res = d->notify_helper(receiver, e);
 
@@ -3112,7 +3112,7 @@ bool QApplication::notify(QObject *receiver, QEvent *e)
                     d->toolTipPos = relpos;
                     d->toolTipGlobalPos = mouse->globalPos();
                     QStyle *s = d->toolTipWidget->style();
-                    int wakeDelay = s->styleHint(QStyle::SH_ToolTip_WakeUpDelay, 0, d->toolTipWidget, 0);
+                    int wakeDelay = s->styleHint(QStyle::SH_ToolTip_WakeUpDelay, nullptr, d->toolTipWidget, nullptr);
                     d->toolTipWakeUp.start(d->toolTipFallAsleep.isActive() ? 20 : wakeDelay, this);
                 }
             }
@@ -3442,7 +3442,7 @@ QT_WARNING_POP
                 && !isProxyWidget
 #endif
                 )
-                QDragManager::self()->setCurrentTarget(0, e->type() == QEvent::Drop);
+                QDragManager::self()->setCurrentTarget(nullptr, e->type() == QEvent::Drop);
         }
         break;
 #endif
@@ -3473,7 +3473,7 @@ QT_WARNING_POP
             eventAccepted = touchEvent->isAccepted();
             if (p.isNull()) {
                 // widget was deleted
-                widget = 0;
+                widget = nullptr;
             } else {
                 widget->setAttribute(Qt::WA_WState_AcceptedTouchBeginEvent, res && eventAccepted);
             }
@@ -3698,7 +3698,7 @@ bool QApplicationPrivate::notify_helper(QObject *receiver, QEvent * e)
 
 bool QApplicationPrivate::inPopupMode()
 {
-    return QApplicationPrivate::popupWidgets != 0;
+    return QApplicationPrivate::popupWidgets != nullptr;
 }
 
 static void ungrabKeyboardForPopup(QWidget *popup)
@@ -3742,13 +3742,13 @@ void QApplicationPrivate::closePopup(QWidget *popup)
     popupWidgets->removeAll(popup);
 
      if (popup == qt_popup_down) {
-         qt_button_down = 0;
-         qt_popup_down = 0;
+         qt_button_down = nullptr;
+         qt_popup_down = nullptr;
      }
 
     if (QApplicationPrivate::popupWidgets->count() == 0) { // this was the last popup
         delete QApplicationPrivate::popupWidgets;
-        QApplicationPrivate::popupWidgets = 0;
+        QApplicationPrivate::popupWidgets = nullptr;
 
         if (popupGrabOk) {
             popupGrabOk = false;
@@ -4116,7 +4116,7 @@ void QApplicationPrivate::giveFocusAccordingToFocusPolicy(QWidget *widget, QEven
 {
     const bool setFocusOnRelease = QGuiApplication::styleHints()->setFocusOnTouchRelease();
     Qt::FocusPolicy focusPolicy = Qt::ClickFocus;
-    static QPointer<QWidget> focusedWidgetOnTouchBegin = 0;
+    static QPointer<QWidget> focusedWidgetOnTouchBegin = nullptr;
 
     switch (event->type()) {
         case QEvent::MouseButtonPress:
@@ -4223,7 +4223,7 @@ QWidget *QApplicationPrivate::findClosestTouchPointTarget(QTouchDevice *device,
 {
     const QPointF screenPos = touchPoint.screenPos();
     int closestTouchPointId = -1;
-    QObject *closestTarget = 0;
+    QObject *closestTarget = nullptr;
     qreal closestDistance = qreal(0.);
     QHash<ActiveTouchPointsKey, ActiveTouchPointsValue>::const_iterator it = activeTouchPoints.constBegin(),
             ite = activeTouchPoints.constEnd();
@@ -4309,7 +4309,7 @@ bool QApplicationPrivate::translateRawTouchEvent(QWidget *window,
             if (!target)
                 continue;
         }
-        Q_ASSERT(target.data() != 0);
+        Q_ASSERT(target.data() != nullptr);
 
         QWidget *targetWidget = static_cast<QWidget *>(target.data());
 
@@ -4335,7 +4335,7 @@ bool QApplicationPrivate::translateRawTouchEvent(QWidget *window,
     const QHash<QWidget *, StatesAndTouchPoints>::ConstIterator end = widgetsNeedingEvents.constEnd();
     for (; it != end; ++it) {
         const QPointer<QWidget> widget = it.key();
-        if (!QApplicationPrivate::tryModalHelper(widget, 0))
+        if (!QApplicationPrivate::tryModalHelper(widget, nullptr))
             continue;
 
         QEvent::Type eventType;
@@ -4462,7 +4462,7 @@ QGestureManager* QGestureManager::instance(InstanceCreation ic)
 {
     QApplicationPrivate *qAppPriv = QApplicationPrivate::instance();
     if (!qAppPriv)
-        return 0;
+        return nullptr;
     if (!qAppPriv->gestureManager && ic == ForceCreation)
         qAppPriv->gestureManager = new QGestureManager(qApp);
     return qAppPriv->gestureManager;
diff --git a/src/widgets/kernel/qboxlayout.cpp b/src/widgets/kernel/qboxlayout.cpp
index 78d37f381e..7b09adfbf0 100644
--- a/src/widgets/kernel/qboxlayout.cpp
+++ b/src/widgets/kernel/qboxlayout.cpp
@@ -278,7 +278,7 @@ void QBoxLayoutPrivate::setupGeom()
     int fixedSpacing = q->spacing();
     int previousNonEmptyIndex = -1;
 
-    QStyle *style = 0;
+    QStyle *style = nullptr;
     if (fixedSpacing < 0) {
         if (QWidget *parentWidget = q->parentWidget())
             style = parentWidget->style();
@@ -318,7 +318,7 @@ void QBoxLayoutPrivate::setupGeom()
                     if (style) {
                         spacing = style->combinedLayoutSpacing(actual1, actual2,
                                              horz(dir) ? Qt::Horizontal : Qt::Vertical,
-                                             0, q->parentWidget());
+                                             nullptr, q->parentWidget());
                         if (spacing < 0)
                             spacing = 0;
                     }
@@ -433,10 +433,10 @@ QLayoutItem* QBoxLayoutPrivate::replaceAt(int index, QLayoutItem *item)
 {
     Q_Q(QBoxLayout);
     if (!item)
-        return 0;
+        return nullptr;
     QBoxLayoutItem *b = list.value(index);
     if (!b)
-        return 0;
+        return nullptr;
     QLayoutItem *r = b->item;
 
     b->item = item;
@@ -551,7 +551,7 @@ QLayoutItem* QBoxLayoutPrivate::replaceAt(int index, QLayoutItem *item)
     \sa direction()
 */
 QBoxLayout::QBoxLayout(Direction dir, QWidget *parent)
-    : QLayout(*new QBoxLayoutPrivate, 0, parent)
+    : QLayout(*new QBoxLayoutPrivate, nullptr, parent)
 {
     Q_D(QBoxLayout);
     d->dir = dir;
@@ -684,7 +684,7 @@ int QBoxLayout::minimumHeightForWidth(int w) const
     Q_D(const QBoxLayout);
     (void) heightForWidth(w);
     int top, bottom;
-    d->effectiveMargins(0, &top, 0, &bottom);
+    d->effectiveMargins(nullptr, &top, nullptr, &bottom);
     return d->hasHfw ? (d->hfwMinHeight + top + bottom) : -1;
 }
 
@@ -713,7 +713,7 @@ int QBoxLayout::count() const
 QLayoutItem *QBoxLayout::itemAt(int index) const
 {
     Q_D(const QBoxLayout);
-    return index >= 0 && index < d->list.count() ? d->list.at(index)->item : 0;
+    return index >= 0 && index < d->list.count() ? d->list.at(index)->item : nullptr;
 }
 
 /*!
@@ -723,16 +723,16 @@ QLayoutItem *QBoxLayout::takeAt(int index)
 {
     Q_D(QBoxLayout);
     if (index < 0 || index >= d->list.count())
-        return 0;
+        return nullptr;
     QBoxLayoutItem *b = d->list.takeAt(index);
     QLayoutItem *item = b->item;
-    b->item = 0;
+    b->item = nullptr;
     delete b;
 
     if (QLayout *l = item->layout()) {
         // sanity check in case the user passed something weird to QObject::setParent()
         if (l->parent() == this)
-            l->setParent(0);
+            l->setParent(nullptr);
     }
 
     invalidate();
diff --git a/src/widgets/kernel/qdesktopwidget.cpp b/src/widgets/kernel/qdesktopwidget.cpp
index 9e90adec46..9f98af86e3 100644
--- a/src/widgets/kernel/qdesktopwidget.cpp
+++ b/src/widgets/kernel/qdesktopwidget.cpp
@@ -205,7 +205,7 @@ QT_WARNING_POP
 }
 
 QDesktopWidget::QDesktopWidget()
-    : QWidget(*new QDesktopWidgetPrivate, 0, Qt::Desktop)
+    : QWidget(*new QDesktopWidgetPrivate, nullptr, Qt::Desktop)
 {
     Q_D(QDesktopWidget);
     setObjectName(QLatin1String("desktop"));
diff --git a/src/widgets/kernel/qformlayout.cpp b/src/widgets/kernel/qformlayout.cpp
index c2838083f3..4ffa226d7f 100644
--- a/src/widgets/kernel/qformlayout.cpp
+++ b/src/widgets/kernel/qformlayout.cpp
@@ -295,11 +295,11 @@ void QFormLayoutPrivate::updateSizes()
         bool expandH = false;
         bool expandV = false;
 
-        QFormLayoutItem *prevLbl = 0;
-        QFormLayoutItem *prevFld = 0;
+        QFormLayoutItem *prevLbl = nullptr;
+        QFormLayoutItem *prevFld = nullptr;
 
         QWidget *parent = q->parentWidget();
-        QStyle *style = parent ? parent->style() : 0;
+        QStyle *style = parent ? parent->style() : nullptr;
 
         int userVSpacing = q->verticalSpacing();
         int userHSpacing = wrapAllRows ? 0 : q->horizontalSpacing();
@@ -364,9 +364,9 @@ void QFormLayoutPrivate::updateSizes()
                         QSizePolicy::ControlTypes fldtoptypes =
                             QSizePolicy::ControlTypes(fldtop ? fldtop->controlTypes() : QSizePolicy::DefaultType);
                         if (label && lbltop)
-                            label->vSpace = style->combinedLayoutSpacing(lbltoptypes, lbltypes, Qt::Vertical, 0, parent);
+                            label->vSpace = style->combinedLayoutSpacing(lbltoptypes, lbltypes, Qt::Vertical, nullptr, parent);
                         if (field && fldtop)
-                            field->vSpace = style->combinedLayoutSpacing(fldtoptypes, fldtypes, Qt::Vertical, 0, parent);
+                            field->vSpace = style->combinedLayoutSpacing(fldtoptypes, fldtypes, Qt::Vertical, nullptr, parent);
                     } else {
                         // Side by side..  we have to also consider the spacings to empty cells, which can strangely be more than
                         // non empty cells..
@@ -380,21 +380,21 @@ void QFormLayoutPrivate::updateSizes()
                         // To be compatible to QGridLayout, we have to compare solitary labels & fields with both predecessors
                         if (label) {
                             if (!field) {
-                                int lblspacing = style->combinedLayoutSpacing(lbltoptypes, lbltypes, Qt::Vertical, 0, parent);
-                                int fldspacing = style->combinedLayoutSpacing(fldtoptypes, lbltypes, Qt::Vertical, 0, parent);
+                                int lblspacing = style->combinedLayoutSpacing(lbltoptypes, lbltypes, Qt::Vertical, nullptr, parent);
+                                int fldspacing = style->combinedLayoutSpacing(fldtoptypes, lbltypes, Qt::Vertical, nullptr, parent);
                                 label->vSpace = qMax(lblspacing, fldspacing);
                             } else
-                                label->vSpace = style->combinedLayoutSpacing(lbltoptypes, lbltypes, Qt::Vertical, 0, parent);
+                                label->vSpace = style->combinedLayoutSpacing(lbltoptypes, lbltypes, Qt::Vertical, nullptr, parent);
                         }
 
                         if (field) {
                             // check spacing against both the previous label and field
                             if (!label) {
-                                int lblspacing = style->combinedLayoutSpacing(lbltoptypes, fldtypes, Qt::Vertical, 0, parent);
-                                int fldspacing = style->combinedLayoutSpacing(fldtoptypes, fldtypes, Qt::Vertical, 0, parent);
+                                int lblspacing = style->combinedLayoutSpacing(lbltoptypes, fldtypes, Qt::Vertical, nullptr, parent);
+                                int fldspacing = style->combinedLayoutSpacing(fldtoptypes, fldtypes, Qt::Vertical, nullptr, parent);
                                 field->vSpace = qMax(lblspacing, fldspacing);
                             } else
-                                field->vSpace = style->combinedLayoutSpacing(fldtoptypes, fldtypes, Qt::Vertical, 0, parent);
+                                field->vSpace = style->combinedLayoutSpacing(fldtoptypes, fldtypes, Qt::Vertical, nullptr, parent);
                         }
                     }
                 }
@@ -403,7 +403,7 @@ void QFormLayoutPrivate::updateSizes()
                 // hard-coded the left and right control types so that all the rows have the same
                 // inter-column spacing (otherwise the right column isn't always left aligned)
                 if (userHSpacing < 0 && !wrapAllRows && (label || !field->fullRow) && field)
-                    field->sbsHSpace = style->combinedLayoutSpacing(QSizePolicy::Label, QSizePolicy::LineEdit, Qt::Horizontal, 0, parent);
+                    field->sbsHSpace = style->combinedLayoutSpacing(QSizePolicy::Label, QSizePolicy::LineEdit, Qt::Horizontal, nullptr, parent);
             }
 
             // Now update our min/sizehint widths
@@ -594,13 +594,13 @@ static inline int spacingHelper(QWidget* parent, QStyle *style, int userVSpacing
                     QSizePolicy::ControlTypes(item1 ? item1->controlTypes() : QSizePolicy::DefaultType);
                 int spacing2 = 0;
 
-                spacing = style->combinedLayoutSpacing(itemtypes, prevItem1->controlTypes(), Qt::Vertical, 0, parent);
+                spacing = style->combinedLayoutSpacing(itemtypes, prevItem1->controlTypes(), Qt::Vertical, nullptr, parent);
 
                 // At most of one of item2 and prevItem2 will be nonnull
                 if (item2)
-                    spacing2 = style->combinedLayoutSpacing(item2->controlTypes(), prevItem1->controlTypes(), Qt::Vertical, 0, parent);
+                    spacing2 = style->combinedLayoutSpacing(item2->controlTypes(), prevItem1->controlTypes(), Qt::Vertical, nullptr, parent);
                 else if (prevItem2)
-                    spacing2 = style->combinedLayoutSpacing(itemtypes, prevItem2->controlTypes(), Qt::Vertical, 0, parent);
+                    spacing2 = style->combinedLayoutSpacing(itemtypes, prevItem2->controlTypes(), Qt::Vertical, nullptr, parent);
 
                 spacing = qMax(spacing, spacing2);
             }
@@ -648,7 +648,7 @@ void QFormLayoutPrivate::setupVerticalLayoutData(int width)
     vLayouts.clear();
     vLayouts.resize((2 * rr) + 2); // a max, some may be unused
 
-    QStyle *style = 0;
+    QStyle *style = nullptr;
 
     int userVSpacing = q->verticalSpacing();
 
@@ -676,8 +676,8 @@ void QFormLayoutPrivate::setupVerticalLayoutData(int width)
         maxLabelWidth = width;
     }
 
-    QFormLayoutItem *prevItem1 = 0;
-    QFormLayoutItem *prevItem2 = 0;
+    QFormLayoutItem *prevItem1 = nullptr;
+    QFormLayoutItem *prevItem2 = nullptr;
     bool prevRowSplit = false;
 
     for (int i = 0; i < rr; ++i) {
@@ -711,13 +711,13 @@ void QFormLayoutPrivate::setupVerticalLayoutData(int width)
                 initLayoutStruct(vLayouts[vidx], label);
 
                 if (vidx > 1)
-                    vLayouts[vidx - 1].spacing = spacingHelper(q->parentWidget(), style, userVSpacing, splitSideBySide || prevRowSplit, label, 0, prevItem1, prevItem2);
+                    vLayouts[vidx - 1].spacing = spacingHelper(q->parentWidget(), style, userVSpacing, splitSideBySide || prevRowSplit, label, nullptr, prevItem1, prevItem2);
 
                 label->vLayoutIndex = vidx;
                 label->sideBySide = false;
 
                 prevItem1 = label;
-                prevItem2 = 0;
+                prevItem2 = nullptr;
 
                 if (vLayouts[vidx].stretch > 0)
                     addTopBottomStretch = false;
@@ -729,13 +729,13 @@ void QFormLayoutPrivate::setupVerticalLayoutData(int width)
                 initLayoutStruct(vLayouts[vidx], field);
 
                 if (vidx > 1)
-                    vLayouts[vidx - 1].spacing = spacingHelper(q->parentWidget(), style, userVSpacing, splitSideBySide || prevRowSplit, field, 0, prevItem1, prevItem2);
+                    vLayouts[vidx - 1].spacing = spacingHelper(q->parentWidget(), style, userVSpacing, splitSideBySide || prevRowSplit, field, nullptr, prevItem1, prevItem2);
 
                 field->vLayoutIndex = vidx;
                 field->sideBySide = false;
 
                 prevItem1 = field;
-                prevItem2 = 0;
+                prevItem2 = nullptr;
 
                 if (vLayouts[vidx].stretch > 0)
                     addTopBottomStretch = false;
@@ -758,7 +758,7 @@ void QFormLayoutPrivate::setupVerticalLayoutData(int width)
                 if (label->expandingDirections() & Qt::Vertical)
                     expanding = true;
 
-                label->sideBySide = (field != 0);
+                label->sideBySide = (field != nullptr);
                 label->vLayoutIndex = vidx;
                 stretch1 = label->vStretch();
             }
@@ -790,7 +790,7 @@ void QFormLayoutPrivate::setupVerticalLayoutData(int width)
                 prevItem2 = field;
             } else {
                 prevItem1 = field;
-                prevItem2 = 0;
+                prevItem2 = nullptr;
             }
 
             prevRowSplit = false;
@@ -991,12 +991,12 @@ QLayoutItem* QFormLayoutPrivate::replaceAt(int index, QLayoutItem *newitem)
 {
     Q_Q(QFormLayout);
     if (!newitem)
-        return 0;
+        return nullptr;
     const int storageIndex = storageIndexFromLayoutItem(m_matrix, m_things.value(index));
     if (Q_UNLIKELY(storageIndex == -1)) {
         // ### Qt6 - fix warning too when this class becomes public
         qWarning("QFormLayoutPrivate::replaceAt: Invalid index %d", index);
-        return 0;
+        return nullptr;
     }
 
     int row, col;
@@ -1192,7 +1192,7 @@ QLayoutItem* QFormLayoutPrivate::replaceAt(int index, QLayoutItem *newitem)
     \sa QWidget::setLayout()
 */
 QFormLayout::QFormLayout(QWidget *parent)
-    : QLayout(*new QFormLayoutPrivate, 0, parent)
+    : QLayout(*new QFormLayoutPrivate, nullptr, parent)
 {
 }
 
@@ -1328,7 +1328,7 @@ void QFormLayout::insertRow(int row, const QString &labelText, QWidget *field)
     if (field && !d->checkWidget(field))
         return;
 
-    QLabel *label = 0;
+    QLabel *label = nullptr;
     if (!labelText.isEmpty()) {
         label = new QLabel(labelText);
 #ifndef QT_NO_SHORTCUT
@@ -1350,7 +1350,7 @@ void QFormLayout::insertRow(int row, const QString &labelText, QLayout *field)
     if (field && !d->checkLayout(field))
         return;
 
-    insertRow(row, labelText.isEmpty() ? 0 : new QLabel(labelText), field);
+    insertRow(row, labelText.isEmpty() ? nullptr : new QLabel(labelText), field);
 }
 
 /*!
@@ -1653,7 +1653,7 @@ QLayoutItem *QFormLayout::itemAt(int index) const
     Q_D(const QFormLayout);
     if (QFormLayoutItem *formItem = d->m_things.value(index))
         return formItem->item;
-    return 0;
+    return nullptr;
 }
 
 /*!
@@ -1666,7 +1666,7 @@ QLayoutItem *QFormLayout::takeAt(int index)
     const int storageIndex = storageIndexFromLayoutItem(d->m_matrix, d->m_things.value(index));
     if (Q_UNLIKELY(storageIndex == -1)) {
         qWarning("QFormLayout::takeAt: Invalid index %d", index);
-        return 0;
+        return nullptr;
     }
 
     int row, col;
@@ -1831,7 +1831,7 @@ QLayoutItem *QFormLayout::itemAt(int row, ItemRole role) const
 {
     Q_D(const QFormLayout);
     if (uint(row) >= uint(d->m_matrix.rowCount()))
-        return 0;
+        return nullptr;
     switch (role) {
     case SpanningRole:
         if (QFormLayoutItem *item = d->m_matrix(row, 1))
@@ -1844,7 +1844,7 @@ QLayoutItem *QFormLayout::itemAt(int row, ItemRole role) const
             return item->item;
         break;
     }
-    return 0;
+    return nullptr;
 }
 
 /*!
@@ -1928,7 +1928,7 @@ QWidget *QFormLayout::labelForField(QWidget *field) const
         if (QFormLayoutItem *label = d->m_matrix(row, LabelRole))
             return label->widget();
     }
-    return 0;
+    return nullptr;
 }
 
 /*!
@@ -1947,7 +1947,7 @@ QWidget *QFormLayout::labelForField(QLayout *field) const
         if (QFormLayoutItem *label = d->m_matrix(row, LabelRole))
             return label->widget();
     }
-    return 0;
+    return nullptr;
 }
 
 /*!
diff --git a/src/widgets/kernel/qgesture.cpp b/src/widgets/kernel/qgesture.cpp
index fc715687c6..84dbed7043 100644
--- a/src/widgets/kernel/qgesture.cpp
+++ b/src/widgets/kernel/qgesture.cpp
@@ -879,7 +879,7 @@ int QTapAndHoldGesturePrivate::Timeout = 700; // in ms
     Creates new QGestureEvent containing a list of \a gestures.
 */
 QGestureEvent::QGestureEvent(const QList<QGesture *> &gestures)
-    : QEvent(QEvent::Gesture), m_gestures(gestures), m_widget(0)
+    : QEvent(QEvent::Gesture), m_gestures(gestures), m_widget(nullptr)
 
 {
 }
@@ -907,7 +907,7 @@ QGesture *QGestureEvent::gesture(Qt::GestureType type) const
     for (int i = 0; i < m_gestures.size(); ++i)
         if (m_gestures.at(i)->gestureType() == type)
             return m_gestures.at(i);
-    return 0;
+    return nullptr;
 }
 
 /*!
diff --git a/src/widgets/kernel/qgesturemanager.cpp b/src/widgets/kernel/qgesturemanager.cpp
index d0c6b882b5..5604391059 100644
--- a/src/widgets/kernel/qgesturemanager.cpp
+++ b/src/widgets/kernel/qgesturemanager.cpp
@@ -188,7 +188,7 @@ QGesture *QGestureManager::getState(QObject *object, QGestureRecognizer *recogni
     // from the destructor.
     if (object->isWidgetType()) {
         if (static_cast<QWidget *>(object)->d_func()->data.in_destructor)
-            return 0;
+            return nullptr;
     } else if (QGesture *g = qobject_cast<QGesture *>(object)) {
         return g;
 #if QT_CONFIG(graphicsview)
@@ -196,7 +196,7 @@ QGesture *QGestureManager::getState(QObject *object, QGestureRecognizer *recogni
         Q_ASSERT(qobject_cast<QGraphicsObject *>(object));
         QGraphicsObject *graphicsObject = static_cast<QGraphicsObject *>(object);
         if (graphicsObject->QGraphicsItem::d_func()->inDestructor)
-            return 0;
+            return nullptr;
 #endif
     }
 
@@ -210,7 +210,7 @@ QGesture *QGestureManager::getState(QObject *object, QGestureRecognizer *recogni
     Q_ASSERT(recognizer);
     QGesture *state = recognizer->create(object);
     if (!state)
-        return 0;
+        return nullptr;
     state->setParent(this);
     if (state->gestureType() == Qt::CustomGesture) {
         // if the recognizer didn't fill in the gesture type, then this
@@ -454,13 +454,13 @@ void QGestureManager::cancelGesturesForChildren(QGesture *original)
     // sort them per target widget by cherry picking from almostCanceledGestures and delivering
     QSet<QGesture *> almostCanceledGestures = cancelledGestures;
     while (!almostCanceledGestures.isEmpty()) {
-        QWidget *target = 0;
+        QWidget *target = nullptr;
         QSet<QGesture*> gestures;
         iter = almostCanceledGestures.begin();
         // sort per target widget
         while (iter != almostCanceledGestures.end()) {
             QWidget *widget = m_gestureTargets.value(*iter);
-            if (target == 0)
+            if (target == nullptr)
                 target = widget;
             if (target == widget) {
                 gestures << *iter;
@@ -508,7 +508,7 @@ bool QGestureManager::filterEvent(QWidget *receiver, QEvent *event)
         }
     }
     // find all gesture contexts for the widget tree
-    w = w->isWindow() ? 0 : w->parentWidget();
+    w = w->isWindow() ? nullptr : w->parentWidget();
     while (w)
     {
         for (ContextIterator it = w->d_func()->gestureContext.constBegin(),
@@ -587,7 +587,7 @@ void QGestureManager::getGestureTargets(const QSet<QGesture*> &gestures,
 
     // sort gestures by types
     foreach (QGesture *gesture, gestures) {
-        QWidget *receiver = m_gestureTargets.value(gesture, 0);
+        QWidget *receiver = m_gestureTargets.value(gesture, nullptr);
         Q_ASSERT(receiver);
         if (receiver)
             gestureByTypes[gesture->gestureType()].insert(receiver, gesture);
@@ -611,7 +611,7 @@ void QGestureManager::getGestureTargets(const QSet<QGesture*> &gestures,
                     }
                 }
                 if (w->isWindow()) {
-                    w = 0;
+                    w = nullptr;
                     break;
                 }
                 w = w->parentWidget();
@@ -637,7 +637,7 @@ void QGestureManager::deliverEvents(const QSet<QGesture *> &gestures,
     for (QSet<QGesture *>::const_iterator it = gestures.begin(),
          e = gestures.end(); it != e; ++it) {
         QGesture *gesture = *it;
-        QWidget *target = m_gestureTargets.value(gesture, 0);
+        QWidget *target = m_gestureTargets.value(gesture, nullptr);
         if (!target) {
             // the gesture has just started and doesn't have a target yet.
             Q_ASSERT(gesture->state() == Qt::GestureStarted);
diff --git a/src/widgets/kernel/qgridlayout.cpp b/src/widgets/kernel/qgridlayout.cpp
index 4f2b505e32..b4ac263c2b 100644
--- a/src/widgets/kernel/qgridlayout.cpp
+++ b/src/widgets/kernel/qgridlayout.cpp
@@ -84,7 +84,7 @@ public:
     Qt::Alignment alignment() const { return item_->alignment(); }
     QLayoutItem *item() { return item_; }
     void setItem(QLayoutItem *newitem) { item_ = newitem; }
-    QLayoutItem *takeItem() { QLayoutItem *i = item_; item_ = 0; return i; }
+    QLayoutItem *takeItem() { QLayoutItem *i = item_; item_ = nullptr; return i; }
 
     int hStretch() { return item_->widget() ?
                          item_->widget()->sizePolicy().horizontalStretch() : 0; }
@@ -152,7 +152,7 @@ public:
         if (index < things.count())
             return things.at(index)->item();
         else
-            return 0;
+            return nullptr;
     }
     inline QLayoutItem *takeAt(int index) {
         Q_Q(QGridLayout);
@@ -162,19 +162,19 @@ public:
                 if (QLayout *l = item->layout()) {
                     // sanity check in case the user passed something weird to QObject::setParent()
                     if (l->parent() == q)
-                        l->setParent(0);
+                        l->setParent(nullptr);
                 }
                 delete b;
                 return item;
             }
         }
-        return 0;
+        return nullptr;
     }
     QLayoutItem* replaceAt(int index, QLayoutItem *newitem) override
     {
         if (!newitem)
-            return 0;
-        QLayoutItem *item = 0;
+            return nullptr;
+        QLayoutItem *item = nullptr;
         QGridBox *b = things.value(index);
         if (b) {
             item = b->takeItem();
@@ -342,7 +342,7 @@ QGridLayoutPrivate::QGridLayoutPrivate()
     setDirty();
     rr = cc = 0;
     nextR = nextC = 0;
-    hfwData = 0;
+    hfwData = nullptr;
     hReversed = false;
     vReversed = false;
     horizontalSpacing = -1;
@@ -429,7 +429,7 @@ int QGridLayoutPrivate::minimumHeightForWidth(int w, int hSpacing, int vSpacing)
     if (!has_hfw)
         return -1;
     int top, bottom;
-    effectiveMargins(0, &top, 0, &bottom);
+    effectiveMargins(nullptr, &top, nullptr, &bottom);
     return hfw_minheight + top + bottom;
 }
 
@@ -521,7 +521,7 @@ void QGridLayoutPrivate::setSize(int r, int c)
 
     if (hfwData && (int)hfwData->size() < r) {
         delete hfwData;
-        hfwData = 0;
+        hfwData = nullptr;
         hfw_width = -1;
     }
     rr = r;
@@ -710,14 +710,14 @@ void QGridLayoutPrivate::setupSpacings(QVector<QLayoutStruct> &chain,
         qSwap(numRows, numColumns);
     }
 
-    QStyle *style = 0;
+    QStyle *style = nullptr;
     if (fixedSpacing < 0) {
         if (QWidget *parentWidget = q->parentWidget())
             style = parentWidget->style();
     }
 
     for (int c = 0; c < numColumns; ++c) {
-        QGridBox *previousBox = 0;
+        QGridBox *previousBox = nullptr;
         int previousRow = -1;       // previous *non-empty* row
 
         for (int r = 0; r < numRows; ++r) {
@@ -741,7 +741,7 @@ void QGridLayoutPrivate::setupSpacings(QVector<QLayoutStruct> &chain,
 
                     if (style)
                         spacing = style->combinedLayoutSpacing(controlTypes1, controlTypes2,
-                                             orientation, 0, q->parentWidget());
+                                             orientation, nullptr, q->parentWidget());
                 } else {
                     if (orientation == Qt::Vertical) {
                         QGridBox *sibling = vReversed ? previousBox : box;
@@ -1075,7 +1075,7 @@ QRect QGridLayoutPrivate::cellRect(int row, int col) const
     new items are inserted.
 */
 QGridLayout::QGridLayout(QWidget *parent)
-    : QLayout(*new QGridLayoutPrivate, 0, parent)
+    : QLayout(*new QGridLayoutPrivate, nullptr, parent)
 {
     Q_D(QGridLayout);
     d->expand(1, 1);
@@ -1089,7 +1089,7 @@ QGridLayout::QGridLayout(QWidget *parent)
     will not be performed before this is inserted into another layout.
 */
 QGridLayout::QGridLayout()
-    : QLayout(*new QGridLayoutPrivate, 0, 0)
+    : QLayout(*new QGridLayoutPrivate, nullptr, nullptr)
 {
     Q_D(QGridLayout);
     d->expand(1, 1);
diff --git a/src/widgets/kernel/qlayout.cpp b/src/widgets/kernel/qlayout.cpp
index f0f4fc5505..d4ff9083f1 100644
--- a/src/widgets/kernel/qlayout.cpp
+++ b/src/widgets/kernel/qlayout.cpp
@@ -130,7 +130,7 @@ QLayout::QLayout(QWidget *parent)
     management will work.
 */
 QLayout::QLayout()
-    : QObject(*new QLayoutPrivate, 0)
+    : QObject(*new QLayoutPrivate, nullptr)
 {
 }
 
@@ -149,14 +149,14 @@ QLayout::QLayout(QLayoutPrivate &dd, QLayout *lay, QWidget *w)
                      " already has a layout",
                      qUtf16Printable(QObject::objectName()), w->metaObject()->className(),
                      qUtf16Printable(w->objectName()));
-            setParent(0);
+            setParent(nullptr);
         } else {
             d->topLevel = true;
             w->d_func()->layout = this;
             QT_TRY {
                 invalidate();
             } QT_CATCH(...) {
-                w->d_func()->layout = 0;
+                w->d_func()->layout = nullptr;
                 QT_RETHROW;
             }
         }
@@ -166,7 +166,7 @@ QLayout::QLayout(QLayoutPrivate &dd, QLayout *lay, QWidget *w)
 QLayoutPrivate::QLayoutPrivate()
     : QObjectPrivate(), insideSpacing(-1), userLeftMargin(-1), userTopMargin(-1), userRightMargin(-1),
       userBottomMargin(-1), topLevel(false), enabled(true), activated(true), autoNewChild(false),
-      constraint(QLayout::SetDefaultConstraint), menubar(0)
+      constraint(QLayout::SetDefaultConstraint), menubar(nullptr)
 {
 }
 
@@ -181,7 +181,7 @@ void QLayoutPrivate::getMargin(int *result, int userMargin, QStyle::PixelMetric
     } else if (!topLevel) {
         *result = 0;
     } else if (QWidget *pw = q->parentWidget()) {
-        *result = pw->style()->pixelMetric(pm, 0, pw);
+        *result = pw->style()->pixelMetric(pm, nullptr, pw);
     } else {
         *result = 0;
     }
@@ -189,8 +189,8 @@ void QLayoutPrivate::getMargin(int *result, int userMargin, QStyle::PixelMetric
 
 // Static item factory functions that allow for hooking things in Designer
 
-QLayoutPrivate::QWidgetItemFactoryMethod QLayoutPrivate::widgetItemFactoryMethod = 0;
-QLayoutPrivate::QSpacerItemFactoryMethod QLayoutPrivate::spacerItemFactoryMethod = 0;
+QLayoutPrivate::QWidgetItemFactoryMethod QLayoutPrivate::widgetItemFactoryMethod = nullptr;
+QLayoutPrivate::QSpacerItemFactoryMethod QLayoutPrivate::spacerItemFactoryMethod = nullptr;
 
 QWidgetItem *QLayoutPrivate::createWidgetItem(const QLayout *layout, QWidget *widget)
 {
@@ -624,7 +624,7 @@ void QLayout::widgetEvent(QEvent *e)
             if (c->child()->isWidgetType()) {
 #if QT_CONFIG(menubar)
                 if (c->child() == d->menubar)
-                    d->menubar = 0;
+                    d->menubar = nullptr;
 #endif
                 removeWidgetRecursively(this, c->child());
             }
@@ -764,7 +764,7 @@ QLayout::~QLayout()
 {
     Q_D(QLayout);
     if (d->topLevel && parent() && parent()->isWidgetType() && parentWidget()->layout() == this)
-        parentWidget()->d_func()->layout = 0;
+        parentWidget()->d_func()->layout = nullptr;
     else if (QLayout *parentLayout = qobject_cast<QLayout *>(parent()))
         parentLayout->removeItem(this);
 }
@@ -919,7 +919,7 @@ void QLayout::addChildWidget(QWidget *w)
                 qWarning("QLayout::addChildWidget: %s \"%ls\" in wrong parent; moved to correct parent",
                          w->metaObject()->className(), qUtf16Printable(w->objectName()));
 #endif
-        pw = 0;
+        pw = nullptr;
     }
     bool needShow = mw && mw->isVisible() && !(w->isHidden() && w->testAttribute(Qt::WA_WState_ExplicitShowHide));
     if (!pw && mw)
@@ -1153,12 +1153,12 @@ QLayoutItem *QLayout::replaceWidget(QWidget *from, QWidget *to, Qt::FindChildOpt
 {
     Q_D(QLayout);
     if (!from || !to)
-        return 0;
+        return nullptr;
     if (from == to)     // Do not return a QLayoutItem for \a from, since ownership still
         return nullptr; // belongs to the layout (since nothing was changed)
 
     int index = -1;
-    QLayoutItem *item = 0;
+    QLayoutItem *item = nullptr;
     for (int u = 0; u < count(); ++u) {
         item = itemAt(u);
         if (!item)
@@ -1176,7 +1176,7 @@ QLayoutItem *QLayout::replaceWidget(QWidget *from, QWidget *to, Qt::FindChildOpt
         }
     }
     if (index == -1)
-        return 0;
+        return nullptr;
 
     addChildWidget(to);
     QLayoutItem *newitem = new QWidgetItem(to);
diff --git a/src/widgets/kernel/qlayoutengine.cpp b/src/widgets/kernel/qlayoutengine.cpp
index 92b362e89d..83bbd69b55 100644
--- a/src/widgets/kernel/qlayoutengine.cpp
+++ b/src/widgets/kernel/qlayoutengine.cpp
@@ -440,7 +440,7 @@ Q_WIDGETS_EXPORT int qSmartSpacing(const QLayout *layout, QStyle::PixelMetric pm
         return -1;
     } else if (parent->isWidgetType()) {
         QWidget *pw = static_cast<QWidget *>(parent);
-        return pw->style()->pixelMetric(pm, 0, pw);
+        return pw->style()->pixelMetric(pm, nullptr, pw);
     } else {
         return static_cast<QLayout *>(parent)->spacing();
     }
diff --git a/src/widgets/kernel/qlayoutitem.cpp b/src/widgets/kernel/qlayoutitem.cpp
index fc02afb014..af5750771d 100644
--- a/src/widgets/kernel/qlayoutitem.cpp
+++ b/src/widgets/kernel/qlayoutitem.cpp
@@ -778,7 +778,7 @@ QWidgetItemV2::QWidgetItemV2(QWidget *widget)
       q_cachedMaximumSize(Dirty, Dirty),
       q_firstCachedHfw(0),
       q_hfwCacheSize(0),
-      d(0)
+      d(nullptr)
 {
     QWidgetPrivate *wd = wid->d_func();
     if (!wd->widgetItem)
@@ -790,7 +790,7 @@ QWidgetItemV2::~QWidgetItemV2()
     if (wid) {
         auto *wd = static_cast<QWidgetPrivate *>(QObjectPrivate::get(wid));
         if (wd->widgetItem == this)
-            wd->widgetItem = 0;
+            wd->widgetItem = nullptr;
     }
 }
 
diff --git a/src/widgets/kernel/qopenglwidget.cpp b/src/widgets/kernel/qopenglwidget.cpp
index bc5ca21b97..90622fd21e 100644
--- a/src/widgets/kernel/qopenglwidget.cpp
+++ b/src/widgets/kernel/qopenglwidget.cpp
@@ -555,16 +555,16 @@ class QOpenGLWidgetPrivate : public QWidgetPrivate
     Q_DECLARE_PUBLIC(QOpenGLWidget)
 public:
     QOpenGLWidgetPrivate()
-        : context(0),
-          fbo(0),
-          resolvedFbo(0),
-          surface(0),
+        : context(nullptr),
+          fbo(nullptr),
+          resolvedFbo(nullptr),
+          surface(nullptr),
           initialized(false),
           fakeHidden(false),
           inBackingStorePaint(false),
           hasBeenComposed(false),
           flushPending(false),
-          paintDevice(0),
+          paintDevice(nullptr),
           updateBehavior(QOpenGLWidget::NoPartialUpdate),
           requestedSamples(0),
           inPaintGL(false),
@@ -704,11 +704,11 @@ void QOpenGLWidgetPrivate::reset()
         q->makeCurrent();
 
     delete paintDevice;
-    paintDevice = 0;
+    paintDevice = nullptr;
     delete fbo;
-    fbo = 0;
+    fbo = nullptr;
     delete resolvedFbo;
-    resolvedFbo = 0;
+    resolvedFbo = nullptr;
 
     if (initialized)
         q->doneCurrent();
@@ -717,9 +717,9 @@ void QOpenGLWidgetPrivate::reset()
     // the context's aboutToBeDestroyed() may still call makeCurrent()
     // to perform some cleanup.
     delete context;
-    context = 0;
+    context = nullptr;
     delete surface;
-    surface = 0;
+    surface = nullptr;
     initialized = fakeHidden = inBackingStorePaint = false;
 }
 
@@ -732,9 +732,9 @@ void QOpenGLWidgetPrivate::recreateFbo()
     context->makeCurrent(surface);
 
     delete fbo;
-    fbo = 0;
+    fbo = nullptr;
     delete resolvedFbo;
-    resolvedFbo = 0;
+    resolvedFbo = nullptr;
 
     int samples = requestedSamples;
     QOpenGLExtensions *extfuncs = static_cast<QOpenGLExtensions *>(context->functions());
@@ -1421,7 +1421,7 @@ QPaintEngine *QOpenGLWidget::paintEngine() const
         return QWidget::paintEngine();
 
     if (!d->initialized)
-        return 0;
+        return nullptr;
 
     return d->paintDevice->paintEngine();
 }
diff --git a/src/widgets/kernel/qstackedlayout.cpp b/src/widgets/kernel/qstackedlayout.cpp
index 0412dc188d..f87fe96cc0 100644
--- a/src/widgets/kernel/qstackedlayout.cpp
+++ b/src/widgets/kernel/qstackedlayout.cpp
@@ -61,11 +61,11 @@ QLayoutItem* QStackedLayoutPrivate::replaceAt(int idx, QLayoutItem *newitem)
 {
     Q_Q(QStackedLayout);
     if (idx < 0 || idx >= list.size() || !newitem)
-        return 0;
+        return nullptr;
     QWidget *wdg = newitem->widget();
     if (Q_UNLIKELY(!wdg)) {
         qWarning("QStackedLayout::replaceAt: Only widgets can be added");
-        return 0;
+        return nullptr;
     }
     QLayoutItem *orgitem = list.at(idx);
     list.replace(idx, newitem);
@@ -154,7 +154,7 @@ QLayoutItem* QStackedLayoutPrivate::replaceAt(int idx, QLayoutItem *newitem)
     \sa addWidget(), insertWidget()
 */
 QStackedLayout::QStackedLayout()
-    : QLayout(*new QStackedLayoutPrivate, 0, 0)
+    : QLayout(*new QStackedLayoutPrivate, nullptr, nullptr)
 {
 }
 
@@ -165,7 +165,7 @@ QStackedLayout::QStackedLayout()
     manage the geometry of its children.
 */
 QStackedLayout::QStackedLayout(QWidget *parent)
-    : QLayout(*new QStackedLayoutPrivate, 0, parent)
+    : QLayout(*new QStackedLayoutPrivate, nullptr, parent)
 {
 }
 
@@ -174,7 +174,7 @@ QStackedLayout::QStackedLayout(QWidget *parent)
     the given \a parentLayout.
 */
 QStackedLayout::QStackedLayout(QLayout *parentLayout)
-    : QLayout(*new QStackedLayoutPrivate, parentLayout, 0)
+    : QLayout(*new QStackedLayoutPrivate, parentLayout, nullptr)
 {
 }
 
@@ -264,7 +264,7 @@ QLayoutItem *QStackedLayout::takeAt(int index)
 {
     Q_D(QStackedLayout);
     if (index <0 || index >= d->list.size())
-        return 0;
+        return nullptr;
     QLayoutItem *item = d->list.takeAt(index);
     if (index == d->index) {
         d->index = -1;
@@ -307,7 +307,7 @@ void QStackedLayout::setCurrentIndex(int index)
         parent->setUpdatesEnabled(false);
     }
 
-    QPointer<QWidget> fw = parent ? parent->window()->focusWidget() : 0;
+    QPointer<QWidget> fw = parent ? parent->window()->focusWidget() : nullptr;
     const bool focusWasOnOldPage = fw && (prev && prev->isAncestorOf(fw));
 
     if (prev) {
diff --git a/src/widgets/kernel/qtooltip.cpp b/src/widgets/kernel/qtooltip.cpp
index 97a279d65d..b290713440 100644
--- a/src/widgets/kernel/qtooltip.cpp
+++ b/src/widgets/kernel/qtooltip.cpp
@@ -151,7 +151,7 @@ public slots:
      */
     void styleSheetParentDestroyed() {
         setProperty("_q_stylesheet_parent", QVariant());
-        styleSheetParent = 0;
+        styleSheetParent = nullptr;
     }
 
 private:
@@ -163,11 +163,11 @@ private:
     QRect rect;
 };
 
-QTipLabel *QTipLabel::instance = 0;
+QTipLabel *QTipLabel::instance = nullptr;
 
 QTipLabel::QTipLabel(const QString &text, const QPoint &pos, QWidget *w, int msecDisplayTime)
 #ifndef QT_NO_STYLE_STYLESHEET
-    : QLabel(w, Qt::ToolTip | Qt::BypassGraphicsProxyWidget), styleSheetParent(0), widget(0)
+    : QLabel(w, Qt::ToolTip | Qt::BypassGraphicsProxyWidget), styleSheetParent(nullptr), widget(nullptr)
 #else
     : QLabel(w, Qt::ToolTip | Qt::BypassGraphicsProxyWidget), widget(0)
 #endif
@@ -178,12 +178,12 @@ QTipLabel::QTipLabel(const QString &text, const QPoint &pos, QWidget *w, int mse
     setBackgroundRole(QPalette::ToolTipBase);
     setPalette(QToolTip::palette());
     ensurePolished();
-    setMargin(1 + style()->pixelMetric(QStyle::PM_ToolTipLabelFrameWidth, 0, this));
+    setMargin(1 + style()->pixelMetric(QStyle::PM_ToolTipLabelFrameWidth, nullptr, this));
     setFrameStyle(QFrame::NoFrame);
     setAlignment(Qt::AlignLeft);
     setIndent(1);
     qApp->installEventFilter(this);
-    setWindowOpacity(style()->styleHint(QStyle::SH_ToolTipLabel_Opacity, 0, this) / 255.0);
+    setWindowOpacity(style()->styleHint(QStyle::SH_ToolTipLabel_Opacity, nullptr, this) / 255.0);
     setMouseTracking(true);
     fadingOut = false;
     reuseTip(text, msecDisplayTime, pos);
@@ -204,7 +204,7 @@ void QTipLabel::reuseTip(const QString &text, int msecDisplayTime, const QPoint
     if (styleSheetParent){
         disconnect(styleSheetParent, SIGNAL(destroyed()),
                    QTipLabel::instance, SLOT(styleSheetParentDestroyed()));
-        styleSheetParent = 0;
+        styleSheetParent = nullptr;
     }
 #endif
 
@@ -278,7 +278,7 @@ void QTipLabel::mouseMoveEvent(QMouseEvent *e)
 
 QTipLabel::~QTipLabel()
 {
-    instance = 0;
+    instance = nullptr;
 }
 
 void QTipLabel::hideTip()
@@ -547,7 +547,7 @@ void QToolTip::showText(const QPoint &pos, const QString &text, QWidget *w)
  */
 bool QToolTip::isVisible()
 {
-    return (QTipLabel::instance != 0 && QTipLabel::instance->isVisible());
+    return (QTipLabel::instance != nullptr && QTipLabel::instance->isVisible());
 }
 
 /*!
diff --git a/src/widgets/kernel/qwhatsthis.cpp b/src/widgets/kernel/qwhatsthis.cpp
index 228ca4d38a..8a632a395a 100644
--- a/src/widgets/kernel/qwhatsthis.cpp
+++ b/src/widgets/kernel/qwhatsthis.cpp
@@ -163,7 +163,7 @@ private:
     QPixmap background;
 };
 
-QWhatsThat *QWhatsThat::instance = 0;
+QWhatsThat *QWhatsThat::instance = nullptr;
 
 // shadowWidth not const, for XP drop-shadow-fu turns it to 0
 static int shadowWidth = 6;   // also used as '5' and '6' and even '8' below
@@ -193,7 +193,7 @@ QWhatsThat::QWhatsThat(const QString& txt, QWidget* parent, QWidget *showTextFor
     setCursor(Qt::ArrowCursor);
 #endif
     QRect r;
-    doc = 0;
+    doc = nullptr;
     ensurePolished(); // Ensures style sheet font before size calc
     if (Qt::mightBeRichText(text)) {
         doc = new QTextDocument();
@@ -229,7 +229,7 @@ QWhatsThat::QWhatsThat(const QString& txt, QWidget* parent, QWidget *showTextFor
 
 QWhatsThat::~QWhatsThat()
 {
-    instance = 0;
+    instance = nullptr;
     if (doc)
         delete doc;
 }
@@ -383,7 +383,7 @@ void QWhatsThisPrivate::notifyToplevels(QEvent *e)
         QCoreApplication::sendEvent(w, e);
 }
 
-QWhatsThisPrivate *QWhatsThisPrivate::instance = 0;
+QWhatsThisPrivate *QWhatsThisPrivate::instance = nullptr;
 
 QWhatsThisPrivate::QWhatsThisPrivate()
     : leaveOnMouseRelease(false)
@@ -423,7 +423,7 @@ QWhatsThisPrivate::~QWhatsThisPrivate()
     QAccessibleEvent event(this, QAccessible::ContextHelpEnd);
     QAccessible::updateAccessibility(&event);
 #endif
-    instance = 0;
+    instance = nullptr;
 }
 
 bool QWhatsThisPrivate::eventFilter(QObject *o, QEvent *e)
@@ -497,7 +497,7 @@ class QWhatsThisAction: public QAction
     Q_OBJECT
 
 public:
-    explicit QWhatsThisAction(QObject* parent = 0);
+    explicit QWhatsThisAction(QObject* parent = nullptr);
 
 private slots:
     void actionTriggered();
@@ -553,7 +553,7 @@ void QWhatsThis::enterWhatsThisMode()
 */
 bool QWhatsThis::inWhatsThisMode()
 {
-    return (QWhatsThisPrivate::instance != 0);
+    return (QWhatsThisPrivate::instance != nullptr);
 }
 
 /*!
@@ -577,7 +577,7 @@ void QWhatsThisPrivate::say(QWidget * widget, const QString &text, int x, int y)
     if (text.size() == 0)
         return;
     // make a fresh widget, and set it up
-    QWhatsThat *whatsThat = new QWhatsThat(text, 0, widget);
+    QWhatsThat *whatsThat = new QWhatsThat(text, nullptr, widget);
 
     // okay, now to find a suitable location
     int scr = (widget ?
diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 9099805cf8..9080c530c7 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -132,16 +132,16 @@ extern QDesktopWidget *qt_desktopWidget; // qapplication.cpp
 
 QWidgetPrivate::QWidgetPrivate(int version)
     : QObjectPrivate(version)
-      , focus_next(0)
-      , focus_prev(0)
-      , focus_child(0)
-      , layout(0)
-      , needsFlush(0)
-      , redirectDev(0)
-      , widgetItem(0)
-      , extraPaintEngine(0)
-      , polished(0)
-      , graphicsEffect(0)
+      , focus_next(nullptr)
+      , focus_prev(nullptr)
+      , focus_child(nullptr)
+      , layout(nullptr)
+      , needsFlush(nullptr)
+      , redirectDev(nullptr)
+      , widgetItem(nullptr)
+      , extraPaintEngine(nullptr)
+      , polished(nullptr)
+      , graphicsEffect(nullptr)
 #if !defined(QT_NO_IM)
       , imHints(Qt::ImhNone)
 #endif
@@ -159,7 +159,7 @@ QWidgetPrivate::QWidgetPrivate(int version)
       , topLayoutItemMargin(0)
       , rightLayoutItemMargin(0)
       , bottomLayoutItemMargin(0)
-      , hd(0)
+      , hd(nullptr)
       , size_policy(QSizePolicy::Preferred, QSizePolicy::Preferred)
       , fg_role(QPalette::NoRole)
       , bg_role(QPalette::NoRole)
@@ -214,7 +214,7 @@ QWidgetPrivate::QWidgetPrivate(int version)
 QWidgetPrivate::~QWidgetPrivate()
 {
     if (widgetItem)
-        widgetItem->wid = 0;
+        widgetItem->wid = nullptr;
 
     if (extra)
         deleteExtra();
@@ -819,8 +819,8 @@ void QWidget::setAutoFillBackground(bool enabled)
 
 */
 
-QWidgetMapper *QWidgetPrivate::mapper = 0;          // widget with wid
-QWidgetSet *QWidgetPrivate::allWidgets = 0;         // widgets with no wid
+QWidgetMapper *QWidgetPrivate::mapper = nullptr;          // widget with wid
+QWidgetSet *QWidgetPrivate::allWidgets = nullptr;         // widgets with no wid
 
 
 /*****************************************************************************
@@ -890,7 +890,7 @@ struct QWidgetExceptionCleaner
     \sa windowFlags
 */
 QWidget::QWidget(QWidget *parent, Qt::WindowFlags f)
-    : QObject(*new QWidgetPrivate, 0), QPaintDevice()
+    : QObject(*new QWidgetPrivate, nullptr), QPaintDevice()
 {
     QT_TRY {
         d_func()->init(parent, f);
@@ -904,7 +904,7 @@ QWidget::QWidget(QWidget *parent, Qt::WindowFlags f)
 /*! \internal
 */
 QWidget::QWidget(QWidgetPrivate &dd, QWidget* parent, Qt::WindowFlags f)
-    : QObject(dd, 0), QPaintDevice()
+    : QObject(dd, nullptr), QPaintDevice()
 {
     Q_D(QWidget);
     QT_TRY {
@@ -996,7 +996,7 @@ void QWidgetPrivate::init(QWidget *parentWidget, Qt::WindowFlags f)
     if (parentWidget && parentWidget->windowType() == Qt::Desktop) {
         const QDesktopScreenWidget *sw = qobject_cast<const QDesktopScreenWidget *>(parentWidget);
         targetScreen = sw ? sw->screenNumber() : 0;
-        parentWidget = 0;
+        parentWidget = nullptr;
     }
 
     q->data = &data;
@@ -1072,7 +1072,7 @@ void QWidgetPrivate::init(QWidget *parentWidget, Qt::WindowFlags f)
     QCoreApplication::sendEvent(q, &e);
     QCoreApplication::postEvent(q, new QEvent(QEvent::PolishRequest));
 
-    extraPaintEngine = 0;
+    extraPaintEngine = nullptr;
 }
 
 void QWidgetPrivate::createRecursively()
@@ -1307,9 +1307,9 @@ void QWidgetPrivate::create()
         if (nativeParent->windowHandle()) {
             if (flags & Qt::Window) {
                 win->setTransientParent(nativeParent->window()->windowHandle());
-                win->setParent(0);
+                win->setParent(nullptr);
             } else {
-                win->setTransientParent(0);
+                win->setTransientParent(nullptr);
                 win->setParent(nativeParent->windowHandle());
             }
         }
@@ -1442,7 +1442,7 @@ QWidget::~QWidget()
 
     // delete layout while we still are a valid widget
     delete d->layout;
-    d->layout = 0;
+    d->layout = nullptr;
     // Remove myself from focus list
 
     Q_ASSERT(d->focus_next->d_func()->focus_prev == this);
@@ -1451,7 +1451,7 @@ QWidget::~QWidget()
     if (d->focus_next != this) {
         d->focus_next->d_func()->focus_prev = d->focus_prev;
         d->focus_prev->d_func()->focus_next = d->focus_next;
-        d->focus_next = d->focus_prev = 0;
+        d->focus_next = d->focus_prev = nullptr;
     }
 
 
@@ -1493,7 +1493,7 @@ QWidget::~QWidget()
     }
 
     delete d->needsFlush;
-    d->needsFlush = 0;
+    d->needsFlush = nullptr;
 
     // The next 20 lines are duplicated from QObject, but required here
     // since QWidget deletes is children itself
@@ -1520,7 +1520,7 @@ QWidget::~QWidget()
             if (QAbstractDeclarativeData::destroyed)
                 QAbstractDeclarativeData::destroyed(d->declarativeData, this);
         }
-        d->declarativeData = 0;                 // don't activate again in ~QObject
+        d->declarativeData = nullptr;                 // don't activate again in ~QObject
         d->wasDeleted = false;
     }
 
@@ -1564,7 +1564,7 @@ void QWidgetPrivate::setWinId(WId id)                // set widget identifier
     // will have the same windowid (the root window id) as the
     // qt_desktopWidget. We should not add the second desktop widget
     // to the mapper.
-    bool userDesktopWidget = qt_desktopWidget != 0 && qt_desktopWidget != q && q->windowType() == Qt::Desktop;
+    bool userDesktopWidget = qt_desktopWidget != nullptr && qt_desktopWidget != q && q->windowType() == Qt::Desktop;
     if (mapper && data.winid && !userDesktopWidget) {
         mapper->remove(data.winid);
     }
@@ -1589,8 +1589,8 @@ void QWidgetPrivate::createTLExtra()
     if (!extra->topextra) {
         extra->topextra = qt_make_unique<QTLWExtra>();
         QTLWExtra* x = extra->topextra.get();
-        x->backingStore = 0;
-        x->sharedPainter = 0;
+        x->backingStore = nullptr;
+        x->sharedPainter = nullptr;
         x->incw = x->inch = 0;
         x->basew = x->baseh = 0;
         x->frameStrut.setCoords(0, 0, 0, 0);
@@ -1601,7 +1601,7 @@ void QWidgetPrivate::createTLExtra()
         x->sizeAdjusted = false;
         x->inTopLevelResize = false;
         x->embedded = 0;
-        x->window = 0;
+        x->window = nullptr;
         x->initialScreenIndex = -1;
 
 #ifdef QWIDGET_EXTRA_DEBUG
@@ -1620,9 +1620,9 @@ void QWidgetPrivate::createExtra()
 {
     if (!extra) {                                // if not exists
         extra = qt_make_unique<QWExtra>();
-        extra->glContext = 0;
+        extra->glContext = nullptr;
 #if QT_CONFIG(graphicsview)
-        extra->proxyWidget = 0;
+        extra->proxyWidget = nullptr;
 #endif
         extra->minw = 0;
         extra->minh = 0;
@@ -1681,7 +1681,7 @@ static void deleteBackingStore(QWidgetPrivate *d)
     QTLWExtra *topData = d->topData();
 
     delete topData->backingStore;
-    topData->backingStore = 0;
+    topData->backingStore = nullptr;
 }
 
 void QWidgetPrivate::deleteTLSysExtra()
@@ -1705,7 +1705,7 @@ void QWidgetPrivate::deleteTLSysExtra()
             extra->topextra->window->destroy();
         }
         delete extra->topextra->window;
-        extra->topextra->window = 0;
+        extra->topextra->window = nullptr;
 
     }
 }
@@ -1805,7 +1805,7 @@ void QWidgetPrivate::paintOnScreen(const QRegion &rgn)
     if (toBePainted.isEmpty())
         return; // Nothing to repaint.
 
-    drawWidget(q, toBePainted, QPoint(), QWidgetPrivate::DrawAsRoot | QWidgetPrivate::DrawPaintOnScreen, 0);
+    drawWidget(q, toBePainted, QPoint(), QWidgetPrivate::DrawAsRoot | QWidgetPrivate::DrawPaintOnScreen, nullptr);
 
     if (Q_UNLIKELY(q->paintingActive()))
         qWarning("QWidget::repaint: It is dangerous to leave painters active on a widget outside of the PaintEvent");
@@ -2302,10 +2302,10 @@ void QWidgetPrivate::deactivateWidgetCleanup()
     Q_Q(QWidget);
     // If this was the active application window, reset it
     if (QApplication::activeWindow() == q)
-        QApplication::setActiveWindow(0);
+        QApplication::setActiveWindow(nullptr);
     // If the is the active mouse press widget, reset it
     if (q == qt_button_down)
-        qt_button_down = 0;
+        qt_button_down = nullptr;
 }
 
 
@@ -2563,7 +2563,7 @@ void QWidget::setStyleSheet(const QString& styleSheet)
     if (testAttribute(Qt::WA_SetStyle)) {
         d->setStyle_helper(new QStyleSheetStyle(d->extra->style), true);
     } else {
-        d->setStyle_helper(new QStyleSheetStyle(0), true);
+        d->setStyle_helper(new QStyleSheetStyle(nullptr), true);
     }
 }
 
@@ -2606,7 +2606,7 @@ QStyle *QWidget::style() const
 void QWidget::setStyle(QStyle *style)
 {
     Q_D(QWidget);
-    setAttribute(Qt::WA_SetStyle, style != 0);
+    setAttribute(Qt::WA_SetStyle, style != nullptr);
     d->createExtra();
 #ifndef QT_NO_STYLE_STYLESHEET
     if (QStyleSheetStyle *styleSheetStyle = qt_styleSheet(style)) {
@@ -2686,7 +2686,7 @@ void QWidgetPrivate::inheritStyle()
 
     QStyle *origStyle = proxy ? proxy->base : extraStyle;
     QWidget *parent = q->parentWidget();
-    QStyle *parentStyle = (parent && parent->d_func()->extra) ? (QStyle*)parent->d_func()->extra->style : 0;
+    QStyle *parentStyle = (parent && parent->d_func()->extra) ? (QStyle*)parent->d_func()->extra->style : nullptr;
     // If we have stylesheet on app or parent has stylesheet style, we need
     // to be running a proxy
     if (!qApp->styleSheet().isEmpty() || qt_styleSheet(parentStyle)) {
@@ -2709,7 +2709,7 @@ void QWidgetPrivate::inheritStyle()
     // In such a case we need to start following the application style (i.e revert
     // the propagation behavior of QStyleSheetStyle)
     if (!q->testAttribute(Qt::WA_SetStyle))
-        origStyle = 0;
+        origStyle = nullptr;
 
     setStyle_helper(origStyle, true);
 #endif // QT_NO_STYLE_STYLESHEET
@@ -3085,7 +3085,7 @@ bool QWidget::isEnabledTo(const QWidget *ancestor) const
 */
 void QWidget::addAction(QAction *action)
 {
-    insertAction(0, action);
+    insertAction(nullptr, action);
 }
 
 /*!
@@ -3100,7 +3100,7 @@ void QWidget::addActions(QList<QAction*> actions)
 #endif
 {
     for(int i = 0; i < actions.count(); i++)
-        insertAction(0, actions.at(i));
+        insertAction(nullptr, actions.at(i));
 }
 
 /*!
@@ -3125,7 +3125,7 @@ void QWidget::insertAction(QAction *before, QAction *action)
 
     int pos = d->actions.indexOf(before);
     if (pos < 0) {
-        before = 0;
+        before = nullptr;
         pos = d->actions.size();
     }
     d->actions.insert(pos, action);
@@ -4606,7 +4606,7 @@ void QWidgetPrivate::updateFont(const QFont &font)
     Q_Q(QWidget);
 #ifndef QT_NO_STYLE_STYLESHEET
     const QStyleSheetStyle* cssStyle;
-    cssStyle = extra ? qt_styleSheet(extra->style) : 0;
+    cssStyle = extra ? qt_styleSheet(extra->style) : nullptr;
     const bool useStyleSheetPropagationInWidgetStyles =
         QCoreApplication::testAttribute(Qt::AA_UseStyleSheetPropagationInWidgetStyles);
 #endif
@@ -4842,7 +4842,7 @@ void qt_qpa_set_cursor(QWidget *w, bool force)
     if (!w->testAttribute(Qt::WA_WState_Created))
         return;
 
-    static QPointer<QWidget> lastUnderMouse = 0;
+    static QPointer<QWidget> lastUnderMouse = nullptr;
     if (force) {
         lastUnderMouse = w;
     } else if (lastUnderMouse) {
@@ -5119,7 +5119,7 @@ void QWidget::setGraphicsEffect(QGraphicsEffect *effect)
     if (d->graphicsEffect) {
         d->invalidateBackingStore(rect());
         delete d->graphicsEffect;
-        d->graphicsEffect = 0;
+        d->graphicsEffect = nullptr;
     }
 
     if (effect) {
@@ -5313,7 +5313,7 @@ void QWidgetPrivate::drawWidget(QPaintDevice *pdev, const QRegion &rgn, const QP
                 setSystemClip(sharedPainter->paintEngine(), 1, QRegion());
                 sharedPainter->restore();
             }
-            sourced->context = 0;
+            sourced->context = nullptr;
 
             if (repaintManager)
                 repaintManager->markNeedsFlush(q, rgn, offset);
@@ -5431,7 +5431,7 @@ void QWidgetPrivate::drawWidget(QPaintDevice *pdev, const QRegion &rgn, const QP
                 if (!sharedPainter)
                     paintEngine->d_func()->systemRect = QRect();
                 else
-                    paintEngine->d_func()->currentClipDevice = 0;
+                    paintEngine->d_func()->currentClipDevice = nullptr;
 
                 setSystemClip(pdev->paintEngine(), 1, QRegion());
             }
@@ -5492,7 +5492,7 @@ void QWidgetPrivate::render(QPaintDevice *target, const QPoint &targetOffset,
     if (paintRegion.isEmpty())
         return;
 
-    QPainter *oldSharedPainter = inRenderWithPainter ? sharedPainter() : 0;
+    QPainter *oldSharedPainter = inRenderWithPainter ? sharedPainter() : nullptr;
 
     // Use the target's shared painter if set (typically set when doing
     // "other->render(widget);" in the widget's paintEvent.
@@ -5553,7 +5553,7 @@ void QWidgetPrivate::paintSiblingsRecursive(QPaintDevice *pdev, const QObjectLis
                                             const QPoint &offset, DrawWidgetFlags flags
                                             , QPainter *sharedPainter, QWidgetRepaintManager *repaintManager)
 {
-    QWidget *w = 0;
+    QWidget *w = nullptr;
     QRect boundingRect;
     bool dirtyBoundingRect = true;
     const bool exludeOpaqueChildren = (flags & DontDrawOpaqueChildren);
@@ -5847,7 +5847,7 @@ QString qt_setWindowTitle_helperHelper(const QString &title, const QWidget *widg
         if (count%2) { // odd number of [*] -> replace last one
             int lastIndex = cap.lastIndexOf(placeHolder, index - 1);
             if (widget->isWindowModified()
-             && widget->style()->styleHint(QStyle::SH_TitleBar_ModifyNotification, 0, widget))
+             && widget->style()->styleHint(QStyle::SH_TitleBar_ModifyNotification, nullptr, widget))
                 cap.replace(lastIndex, 3, QWidget::tr("*"));
             else
                 cap.remove(lastIndex, 3);
@@ -6299,7 +6299,7 @@ void QWidget::setFocus(Qt::FocusReason reason)
         return;
 
 #if QT_CONFIG(graphicsview)
-    QWidget *previousProxyFocus = 0;
+    QWidget *previousProxyFocus = nullptr;
     if (const auto &topData = window()->d_func()->extra) {
         if (topData->proxyWidget && topData->proxyWidget->hasFocus()) {
             previousProxyFocus = topData->proxyWidget->widget()->focusWidget();
@@ -6439,12 +6439,12 @@ void QWidgetPrivate::updateFocusChild()
     if (q->isHidden()) {
         while (w && w->isHidden()) {
             w->d_func()->focus_child = q;
-            w = w->isWindow() ? 0 : w->parentWidget();
+            w = w->isWindow() ? nullptr : w->parentWidget();
         }
     } else {
         while (w) {
             w->d_func()->focus_child = q;
-            w = w->isWindow() ? 0 : w->parentWidget();
+            w = w->isWindow() ? nullptr : w->parentWidget();
         }
     }
 
@@ -6490,7 +6490,7 @@ void QWidget::clearFocus()
     while (w) {
         // Just like setFocus(), we update (clear) the focus_child of our parents
         if (w->d_func()->focus_child == this)
-            w->d_func()->focus_child = 0;
+            w->d_func()->focus_child = nullptr;
         w = w->parentWidget();
     }
 
@@ -6511,7 +6511,7 @@ void QWidget::clearFocus()
 
     if (hasFocus()) {
         // Update proxy state
-        QApplicationPrivate::setFocusWidget(0, Qt::OtherFocusReason);
+        QApplicationPrivate::setFocusWidget(nullptr, Qt::OtherFocusReason);
 #ifndef QT_NO_ACCESSIBILITY
         QAccessibleEvent event(this, QAccessible::Focus);
         QAccessible::updateAccessibility(&event);
@@ -6588,10 +6588,10 @@ bool QWidget::focusNextPrevChild(bool next)
      */
     if (wrappingOccurred) {
         QWindow *window = windowHandle();
-        if (window != 0) {
+        if (window != nullptr) {
             QWindowPrivate *winp = qt_window_private(window);
 
-            if (winp->platformWindow != 0) {
+            if (winp->platformWindow != nullptr) {
                 QFocusEvent event(QEvent::FocusIn, reason);
                 event.ignore();
                 winp->platformWindow->windowEvent(&event);
@@ -6669,7 +6669,7 @@ bool QWidget::isActiveWindow() const
     }
 #endif
 
-    if(style()->styleHint(QStyle::SH_Widget_ShareActivation, 0, this)) {
+    if (style()->styleHint(QStyle::SH_Widget_ShareActivation, nullptr, this)) {
         if(tlw->windowType() == Qt::Tool &&
            !tlw->isModal() &&
            (!tlw->parentWidget() || tlw->parentWidget()->isActiveWindow()))
@@ -6825,9 +6825,9 @@ void QWidgetPrivate::reparentFocusWidgets(QWidget * oldtlw)
         focus_child->clearFocus();
 
     // separate the focus chain into new (children of myself) and old (the rest)
-    QWidget *firstOld = 0;
+    QWidget *firstOld = nullptr;
     //QWidget *firstNew = q; //invariant
-    QWidget *o = 0; // last in the old list
+    QWidget *o = nullptr; // last in the old list
     QWidget *n = q; // last in the new list
 
     bool prevWasNew = true;
@@ -7835,7 +7835,7 @@ void QWidgetPrivate::show_helper()
 #endif
 
     if (QApplicationPrivate::hidden_focus_widget == q) {
-        QApplicationPrivate::hidden_focus_widget = 0;
+        QApplicationPrivate::hidden_focus_widget = nullptr;
         q->setFocus(Qt::OtherFocusReason);
     }
 
@@ -7934,7 +7934,7 @@ void QWidgetPrivate::hide_helper()
 
     bool isEmbedded = false;
 #if QT_CONFIG(graphicsview)
-    isEmbedded = q->isWindow() && !bypassGraphicsProxyWidget(q) && nearestGraphicsProxyWidget(q->parentWidget()) != 0;
+    isEmbedded = q->isWindow() && !bypassGraphicsProxyWidget(q) && nearestGraphicsProxyWidget(q->parentWidget()) != nullptr;
 #else
     Q_UNUSED(isEmbedded);
 #endif
@@ -8127,7 +8127,7 @@ void QWidgetPrivate::setVisible(bool visible)
         QCoreApplication::sendEvent(q, &showToParentEvent);
     } else { // hide
         if (QApplicationPrivate::hidden_focus_widget == q)
-            QApplicationPrivate::hidden_focus_widget = 0;
+            QApplicationPrivate::hidden_focus_widget = nullptr;
 
         // hw: The test on getOpaqueRegion() needs to be more intelligent
         // currently it doesn't work if the widget is hidden (the region will
@@ -8820,7 +8820,7 @@ bool QWidget::event(QEvent *event)
         case Qt::ActionsContextMenu:
             if (d->actions.count()) {
                 QMenu::exec(d->actions, static_cast<QContextMenuEvent *>(event)->globalPos(),
-                            0, this);
+                            nullptr, this);
                 break;
             }
             Q_FALLTHROUGH();
@@ -10012,9 +10012,9 @@ QLayout *QWidget::takeLayout()
     Q_D(QWidget);
     QLayout *l =  layout();
     if (!l)
-        return 0;
-    d->layout = 0;
-    l->setParent(0);
+        return nullptr;
+    d->layout = nullptr;
+    l->setParent(nullptr);
     return l;
 }
 
@@ -10136,10 +10136,10 @@ QWidget *QWidget::childAt(const QPoint &p) const
 QWidget *QWidgetPrivate::childAt_helper(const QPoint &p, bool ignoreChildrenInDestructor) const
 {
     if (children.isEmpty())
-        return 0;
+        return nullptr;
 
     if (!pointInsideRectAndMask(p))
-        return 0;
+        return nullptr;
     return childAtRecursiveHelper(p, ignoreChildrenInDestructor);
 }
 
@@ -10167,7 +10167,7 @@ QWidget *QWidgetPrivate::childAtRecursiveHelper(const QPoint &p, bool ignoreChil
         // We have found our target; namely the child at position 'p'.
         return child;
     }
-    return 0;
+    return nullptr;
 }
 
 void QWidgetPrivate::updateGeometry_helper(bool forceUpdate)
@@ -10380,7 +10380,7 @@ void QWidget::setParent(QWidget *parent, Qt::WindowFlags f)
     if (f & Qt::Window) // Frame geometry likely changes, refresh.
         d->data.fstrut_dirty = true;
 
-    QWidget *desktopWidget = 0;
+    QWidget *desktopWidget = nullptr;
     if (parent && parent->windowType() == Qt::Desktop)
         desktopWidget = parent;
     bool newParent = (parent != parentWidget()) || !wasCreated || desktopWidget;
@@ -10408,7 +10408,7 @@ void QWidget::setParent(QWidget *parent, Qt::WindowFlags f)
     d->setParent_sys(parent, f);
 
     if (desktopWidget)
-        parent = 0;
+        parent = nullptr;
 
 #ifndef QT_NO_OPENGL
     if (d->textureChildSeen && parent) {
@@ -10522,7 +10522,7 @@ void QWidgetPrivate::setParent_sys(QWidget *newparent, Qt::WindowFlags f)
         // programmer specified desktop widget
         const QDesktopScreenWidget *sw = qobject_cast<const QDesktopScreenWidget *>(newparent);
         targetScreen = sw ? sw->screenNumber() : 0;
-        newparent = 0;
+        newparent = nullptr;
     }
 
     setWinId(0);
@@ -10532,19 +10532,19 @@ void QWidgetPrivate::setParent_sys(QWidget *newparent, Qt::WindowFlags f)
         if (q->windowHandle()) {
             q->windowHandle()->setFlags(f);
             QWidget *parentWithWindow =
-                newparent ? (newparent->windowHandle() ? newparent : newparent->nativeParentWidget()) : 0;
+                newparent ? (newparent->windowHandle() ? newparent : newparent->nativeParentWidget()) : nullptr;
             if (parentWithWindow) {
                 QWidget *topLevel = parentWithWindow->window();
                 if ((f & Qt::Window) && topLevel && topLevel->windowHandle()) {
                     q->windowHandle()->setTransientParent(topLevel->windowHandle());
-                    q->windowHandle()->setParent(0);
+                    q->windowHandle()->setParent(nullptr);
                 } else {
-                    q->windowHandle()->setTransientParent(0);
+                    q->windowHandle()->setTransientParent(nullptr);
                     q->windowHandle()->setParent(parentWithWindow->windowHandle());
                 }
             } else {
-                q->windowHandle()->setTransientParent(0);
-                q->windowHandle()->setParent(0);
+                q->windowHandle()->setTransientParent(nullptr);
+                q->windowHandle()->setParent(nullptr);
             }
         }
     }
@@ -10575,7 +10575,7 @@ void QWidgetPrivate::setParent_sys(QWidget *newparent, Qt::WindowFlags f)
                 continue;
 
             QWidgetWindow *childWW = qobject_cast<QWidgetWindow *>(childWindow);
-            QWidget *childWidget = childWW ? childWW->widget() : 0;
+            QWidget *childWidget = childWW ? childWW->widget() : nullptr;
             if (!childWW || (childWidget && childWidget->testAttribute(Qt::WA_NativeWindow)))
                 childWindow->setParent(newParentWindow);
         }
@@ -11981,7 +11981,7 @@ QOpenGLContext *QWidgetPrivate::shareContext() const
     return 0;
 #else
     if (!extra || !extra->topextra || !extra->topextra->window)
-        return 0;
+        return nullptr;
 
     if (!extra->topextra->shareContext) {
         auto ctx = qt_make_unique<QOpenGLContext>();
@@ -12040,7 +12040,7 @@ QGraphicsProxyWidget *QWidget::graphicsProxyWidget() const
     if (d->extra) {
         return d->extra->proxyWidget;
     }
-    return 0;
+    return nullptr;
 }
 #endif
 
@@ -12101,7 +12101,7 @@ void QWidget::destroy(bool destroyWindow, bool destroySubWindows)
         qApp->d_func()->closePopup(this);
 
     if (this == QApplicationPrivate::active_window)
-        QApplication::setActiveWindow(0);
+        QApplication::setActiveWindow(nullptr);
     if (QWidget::mouseGrabber() == this)
         releaseMouse();
     if (QWidget::keyboardGrabber() == this)
@@ -12165,7 +12165,7 @@ QPaintEngine *QWidget::paintEngine() const
     const_cast<QWidgetPrivate *>(d_func())->noPaintOnScreen = 1;
 #endif
 
-    return 0; //##### @@@
+    return nullptr; //##### @@@
 }
 
 // Do not call QWindow::mapToGlobal() until QPlatformWindow is properly showing.
@@ -12252,10 +12252,10 @@ QPoint QWidget::mapFromGlobal(const QPoint &pos) const
    return t.transform.inverted().map(windowLocal);
 }
 
-QWidget *qt_pressGrab = 0;
-QWidget *qt_mouseGrb = 0;
+QWidget *qt_pressGrab = nullptr;
+QWidget *qt_mouseGrb = nullptr;
 static bool mouseGrabWithCursor = false;
-static QWidget *keyboardGrb = 0;
+static QWidget *keyboardGrb = nullptr;
 
 static inline QWindow *grabberWindow(const QWidget *w)
 {
@@ -12267,7 +12267,7 @@ static inline QWindow *grabberWindow(const QWidget *w)
 }
 
 #ifndef QT_NO_CURSOR
-static void grabMouseForWidget(QWidget *widget, const QCursor *cursor = 0)
+static void grabMouseForWidget(QWidget *widget, const QCursor *cursor = nullptr)
 #else
 static void grabMouseForWidget(QWidget *widget)
 #endif
@@ -12287,7 +12287,7 @@ static void grabMouseForWidget(QWidget *widget)
     }
 
     qt_mouseGrb = widget;
-    qt_pressGrab = 0;
+    qt_pressGrab = nullptr;
 }
 
 static void releaseMouseGrabOfWidget(QWidget *widget)
@@ -12303,7 +12303,7 @@ static void releaseMouseGrabOfWidget(QWidget *widget)
             window->setMouseGrabEnabled(false);
         }
     }
-    qt_mouseGrb = 0;
+    qt_mouseGrb = nullptr;
 }
 
 /*!
@@ -12432,7 +12432,7 @@ void QWidget::releaseKeyboard()
     if (keyboardGrb == this) {
         if (QWindow *window = grabberWindow(this))
             window->setKeyboardGrabEnabled(false);
-        keyboardGrb = 0;
+        keyboardGrb = nullptr;
     }
 }
 
@@ -12509,8 +12509,8 @@ void QWidget::activateWindow()
 */
 int QWidget::metric(PaintDeviceMetric m) const
 {
-    QWindow *topLevelWindow = 0;
-    QScreen *screen = 0;
+    QWindow *topLevelWindow = nullptr;
+    QScreen *screen = nullptr;
     if (QWidget *topLevel = window()) {
         topLevelWindow = topLevel->windowHandle();
         if (topLevelWindow)
@@ -12596,14 +12596,14 @@ QPainter *QWidget::sharedPainter() const
 {
     // Someone sent a paint event directly to the widget
     if (!d_func()->redirectDev)
-        return 0;
+        return nullptr;
 
     QPainter *sp = d_func()->sharedPainter();
     if (!sp || !sp->isActive())
-        return 0;
+        return nullptr;
 
     if (sp->paintEngine()->paintDevice() != d_func()->redirectDev)
-        return 0;
+        return nullptr;
 
     return sp;
 }
diff --git a/src/widgets/kernel/qwidget_p.h b/src/widgets/kernel/qwidget_p.h
index 62da3fabf4..6915782cb3 100644
--- a/src/widgets/kernel/qwidget_p.h
+++ b/src/widgets/kernel/qwidget_p.h
@@ -420,7 +420,7 @@ public:
     void setVisible(bool);
 
     void setEnabled_helper(bool);
-    static void adjustFlags(Qt::WindowFlags &flags, QWidget *w = 0);
+    static void adjustFlags(Qt::WindowFlags &flags, QWidget *w = nullptr);
 
     void updateFrameStrut();
     QRect frameStrut() const;
diff --git a/src/widgets/kernel/qwidgetaction.cpp b/src/widgets/kernel/qwidgetaction.cpp
index 6eebaca42c..9649e51b92 100644
--- a/src/widgets/kernel/qwidgetaction.cpp
+++ b/src/widgets/kernel/qwidgetaction.cpp
@@ -146,7 +146,7 @@ void QWidgetAction::setDefaultWidget(QWidget *widget)
 
     setVisible(!(widget->isHidden() && widget->testAttribute(Qt::WA_WState_ExplicitShowHide)));
     d->defaultWidget->hide();
-    d->defaultWidget->setParent(0);
+    d->defaultWidget->setParent(nullptr);
     d->defaultWidgetInUse = false;
     if (!isEnabled())
         d->defaultWidget->setEnabled(false);
@@ -177,7 +177,7 @@ QWidget *QWidgetAction::requestWidget(QWidget *parent)
     QWidget *w = createWidget(parent);
     if (!w) {
         if (d->defaultWidgetInUse || !d->defaultWidget)
-            return 0;
+            return nullptr;
         d->defaultWidget->setParent(parent);
         d->defaultWidgetInUse = true;
         return d->defaultWidget;
@@ -203,7 +203,7 @@ void QWidgetAction::releaseWidget(QWidget *widget)
 
     if (widget == d->defaultWidget) {
         d->defaultWidget->hide();
-        d->defaultWidget->setParent(0);
+        d->defaultWidget->setParent(nullptr);
         d->defaultWidgetInUse = false;
         return;
     }
@@ -251,7 +251,7 @@ bool QWidgetAction::eventFilter(QObject *obj, QEvent *event)
 QWidget *QWidgetAction::createWidget(QWidget *parent)
 {
     Q_UNUSED(parent)
-    return 0;
+    return nullptr;
 }
 
 /*!
diff --git a/src/widgets/kernel/qwidgetrepaintmanager.cpp b/src/widgets/kernel/qwidgetrepaintmanager.cpp
index c3211e275f..135a1527ac 100644
--- a/src/widgets/kernel/qwidgetrepaintmanager.cpp
+++ b/src/widgets/kernel/qwidgetrepaintmanager.cpp
@@ -695,7 +695,7 @@ static QPlatformTextureList *widgetTexturesFor(QWidget *tlw, QWidget *widget)
             return qt_dummy_platformTextureList();
     }
 
-    return 0;
+    return nullptr;
 }
 
 #else
@@ -788,7 +788,7 @@ bool QWidgetRepaintManager::syncAllowed()
     QTLWExtra *tlwExtra = tlw->d_func()->maybeTopData();
     if (textureListWatcher && !textureListWatcher->isLocked()) {
         textureListWatcher->deleteLater();
-        textureListWatcher = 0;
+        textureListWatcher = nullptr;
     } else if (!tlwExtra->widgetTextures.empty()) {
         bool skipSync = false;
         for (const auto &tl : tlwExtra->widgetTextures) {
@@ -822,7 +822,7 @@ void QWidgetRepaintManager::paintAndFlush()
         if (hasStaticContents() && !store->size().isEmpty() ) {
             // Repaint existing dirty area and newly visible area.
             const QRect clipRect(0, 0, surfaceGeometry.width(), surfaceGeometry.height());
-            const QRegion staticRegion(staticContents(0, clipRect));
+            const QRegion staticRegion(staticContents(nullptr, clipRect));
             QRegion newVisible(0, 0, tlwRect.width(), tlwRect.height());
             newVisible -= staticRegion;
             dirty += newVisible;
@@ -1008,13 +1008,13 @@ void QWidgetRepaintManager::paintAndFlush()
         QPoint offset;
         if (w != tlw)
             offset += w->mapTo(tlw, QPoint());
-        wd->drawWidget(store->paintDevice(), toBePainted, offset, flags, 0, this);
+        wd->drawWidget(store->paintDevice(), toBePainted, offset, flags, nullptr, this);
     }
 
     // Paint the rest with composition.
     if (repaintAllWidgets || !dirtyCopy.isEmpty()) {
         QWidgetPrivate::DrawWidgetFlags flags = QWidgetPrivate::DrawAsRoot | QWidgetPrivate::DrawRecursive;
-        tlw->d_func()->drawWidget(store->paintDevice(), dirtyCopy, QPoint(), flags, 0, this);
+        tlw->d_func()->drawWidget(store->paintDevice(), dirtyCopy, QPoint(), flags, nullptr, this);
     }
 
     store->endPaint();
@@ -1108,7 +1108,7 @@ void QWidgetRepaintManager::flush()
     for (QWidget *w : qExchange(needsFlushWidgets, {})) {
         QWidgetPrivate *wd = w->d_func();
         Q_ASSERT(wd->needsFlush);
-        QPlatformTextureList *widgetTexturesForNative = wd->textureChildSeen ? widgetTexturesFor(tlw, w) : 0;
+        QPlatformTextureList *widgetTexturesForNative = wd->textureChildSeen ? widgetTexturesFor(tlw, w) : nullptr;
         flush(w, *wd->needsFlush, widgetTexturesForNative);
         *wd->needsFlush = QRegion();
     }
@@ -1284,7 +1284,7 @@ QRegion QWidgetRepaintManager::staticContents(QWidget *parent, const QRect &with
         wd->clipToEffectiveMask(visible);
         if (visible.isEmpty())
             continue;
-        wd->subtractOpaqueSiblings(visible, 0, /*alsoNonOpaque=*/true);
+        wd->subtractOpaqueSiblings(visible, nullptr, /*alsoNonOpaque=*/true);
 
         visible.translate(offset);
         region += visible;
@@ -1331,7 +1331,7 @@ void QWidgetPrivate::invalidateBackingStore_resizeHelper(const QPoint &oldPos, c
 
     if (!staticContents || graphicsEffect) {
         QRegion staticChildren;
-        QWidgetRepaintManager *bs = 0;
+        QWidgetRepaintManager *bs = nullptr;
         if (offset.isNull() && (bs = maybeRepaintManager()))
             staticChildren = bs->staticContents(q, oldWidgetRect);
         const bool hasStaticChildren = !staticChildren.isEmpty();
diff --git a/src/widgets/kernel/qwidgetsvariant.cpp b/src/widgets/kernel/qwidgetsvariant.cpp
index 02b4ea20a7..41600d2143 100644
--- a/src/widgets/kernel/qwidgetsvariant.cpp
+++ b/src/widgets/kernel/qwidgetsvariant.cpp
@@ -125,12 +125,12 @@ static const QVariant::Handler widgets_handler = {
     clear,
     isNull,
 #ifndef QT_NO_DATASTREAM
-    0,
-    0,
+    nullptr,
+    nullptr,
 #endif
     compare,
     convert,
-    0,
+    nullptr,
 #if !defined(QT_NO_DEBUG_STREAM)
     streamDebug
 #else
diff --git a/src/widgets/kernel/qwidgetwindow.cpp b/src/widgets/kernel/qwidgetwindow.cpp
index 596343c52f..904067afda 100644
--- a/src/widgets/kernel/qwidgetwindow.cpp
+++ b/src/widgets/kernel/qwidgetwindow.cpp
@@ -57,10 +57,10 @@ QT_BEGIN_NAMESPACE
 
 Q_WIDGETS_EXPORT extern bool qt_tab_all_widgets();
 
-Q_WIDGETS_EXPORT QWidget *qt_button_down = 0; // widget got last button-down
+Q_WIDGETS_EXPORT QWidget *qt_button_down = nullptr; // widget got last button-down
 
 // popup control
-QWidget *qt_popup_down = 0; // popup that contains the pressed widget
+QWidget *qt_popup_down = nullptr; // popup that contains the pressed widget
 extern int openPopupCount;
 bool qt_replay_popup_mouse_event = false;
 extern bool qt_try_modal(QWidget *widget, QEvent::Type type);
@@ -156,7 +156,7 @@ QOpenGLContext *QWidgetWindowPrivate::shareContext() const
 #endif // opengl
 
 QWidgetWindow::QWidgetWindow(QWidget *widget)
-    : QWindow(*new QWidgetWindowPrivate(), 0)
+    : QWindow(*new QWidgetWindowPrivate(), nullptr)
     , m_widget(widget)
 {
     updateObjectName();
@@ -179,7 +179,7 @@ QAccessibleInterface *QWidgetWindow::accessibleRoot() const
 {
     if (m_widget)
         return QAccessible::queryAccessibleInterface(m_widget);
-    return 0;
+    return nullptr;
 }
 #endif
 
@@ -374,7 +374,7 @@ bool QWidgetWindow::event(QEvent *event)
 #endif // QT_NO_CONTEXTMENU
 
     case QEvent::WindowBlocked:
-        qt_button_down = 0;
+        qt_button_down = nullptr;
         break;
 
     case QEvent::UpdateRequest:
@@ -393,7 +393,7 @@ bool QWidgetWindow::event(QEvent *event)
     return QWindow::event(event);
 }
 
-QPointer<QWidget> qt_last_mouse_receiver = 0;
+QPointer<QWidget> qt_last_mouse_receiver = nullptr;
 
 void QWidgetWindow::handleEnterLeaveEvent(QEvent *event)
 {
@@ -406,7 +406,7 @@ void QWidgetWindow::handleEnterLeaveEvent(QEvent *event)
         return;
 #endif
     if (event->type() == QEvent::Leave) {
-        QWidget *enter = 0;
+        QWidget *enter = nullptr;
         // Check from window system event queue if the next queued enter targets a window
         // in the same window hierarchy (e.g. enter a child of this window). If so,
         // remove the enter event from queue and handle both in single dispatch.
@@ -484,13 +484,13 @@ QWidget *QWidgetWindow::getFocusWidget(FocusWidgets fw)
 
 void QWidgetWindow::handleFocusInEvent(QFocusEvent *e)
 {
-    QWidget *focusWidget = 0;
+    QWidget *focusWidget = nullptr;
     if (e->reason() == Qt::BacktabFocusReason)
         focusWidget = getFocusWidget(LastFocusWidget);
     else if (e->reason() == Qt::TabFocusReason)
         focusWidget = getFocusWidget(FirstFocusWidget);
 
-    if (focusWidget != 0)
+    if (focusWidget != nullptr)
         focusWidget->setFocus();
 }
 
@@ -513,8 +513,8 @@ void QWidgetWindow::handleMouseEvent(QMouseEvent *event)
         QWidget *popupChild  = activePopupWidget->childAt(mapped);
 
         if (activePopupWidget != qt_popup_down) {
-            qt_button_down = 0;
-            qt_popup_down = 0;
+            qt_button_down = nullptr;
+            qt_popup_down = nullptr;
         }
 
         switch (event->type()) {
@@ -589,7 +589,7 @@ void QWidgetWindow::handleMouseEvent(QMouseEvent *event)
             && qt_replay_popup_mouse_event
             && QGuiApplicationPrivate::platformIntegration()->styleHint(QPlatformIntegration::ReplayMousePressOutsidePopup).toBool()) {
             if (m_widget->windowType() != Qt::Popup)
-                qt_button_down = 0;
+                qt_button_down = nullptr;
             if (event->type() == QEvent::MouseButtonPress) {
                 // the popup disappeared, replay the mouse press event
                 QWidget *w = QApplication::widgetAt(event->globalPos());
@@ -636,8 +636,8 @@ void QWidgetWindow::handleMouseEvent(QMouseEvent *event)
 #endif
 
         if (releaseAfter) {
-            qt_button_down = 0;
-            qt_popup_down = 0;
+            qt_button_down = nullptr;
+            qt_popup_down = nullptr;
         }
         return;
     }
@@ -1050,7 +1050,7 @@ bool QWidgetWindow::nativeEvent(const QByteArray &eventType, void *message, long
 #if QT_CONFIG(tabletevent)
 void QWidgetWindow::handleTabletEvent(QTabletEvent *event)
 {
-    static QPointer<QWidget> qt_tablet_target = 0;
+    static QPointer<QWidget> qt_tablet_target = nullptr;
 
     QWidget *widget = qt_tablet_target;
 
@@ -1076,7 +1076,7 @@ void QWidgetWindow::handleTabletEvent(QTabletEvent *event)
     }
 
     if (event->type() == QEvent::TabletRelease && event->buttons() == Qt::NoButton)
-        qt_tablet_target = 0;
+        qt_tablet_target = nullptr;
 }
 #endif // QT_CONFIG(tabletevent)
 
@@ -1084,7 +1084,7 @@ void QWidgetWindow::handleTabletEvent(QTabletEvent *event)
 void QWidgetWindow::handleGestureEvent(QNativeGestureEvent *e)
 {
     // copy-pasted code to find correct widget follows:
-    QObject *receiver = 0;
+    QObject *receiver = nullptr;
     if (QApplicationPrivate::inPopupMode()) {
         QWidget *popup = QApplication::activePopupWidget();
         QWidget *popupFocusWidget = popup->focusWidget();
diff --git a/src/widgets/kernel/qwindowcontainer.cpp b/src/widgets/kernel/qwindowcontainer.cpp
index fd8581edbb..b4d889fdfa 100644
--- a/src/widgets/kernel/qwindowcontainer.cpp
+++ b/src/widgets/kernel/qwindowcontainer.cpp
@@ -58,8 +58,8 @@ public:
     Q_DECLARE_PUBLIC(QWindowContainer)
 
     QWindowContainerPrivate()
-        : window(0)
-        , oldFocusWindow(0)
+        : window(nullptr)
+        , oldFocusWindow(nullptr)
         , usesNativeWidgets(false)
     {
     }
@@ -70,7 +70,7 @@ public:
         QWindowContainer *wc = qobject_cast<QWindowContainer *>(w);
         if (wc)
             return wc->d_func();
-        return 0;
+        return nullptr;
     }
 
     void updateGeometry() {
@@ -90,7 +90,7 @@ public:
 
     void updateUsesNativeWidgets()
     {
-        if (window->parent() == 0)
+        if (window->parent() == nullptr)
             return;
         Q_Q(QWindowContainer);
         if (q->internalWinId()) {
@@ -295,7 +295,7 @@ bool QWindowContainer::event(QEvent *e)
     case QEvent::ChildRemoved: {
         QChildEvent *ce = static_cast<QChildEvent *>(e);
         if (ce->child() == d->window)
-            d->window = 0;
+            d->window = nullptr;
         break;
     }
     // The only thing we are interested in is making sure our sizes stay
diff --git a/src/widgets/statemachine/qguistatemachine.cpp b/src/widgets/statemachine/qguistatemachine.cpp
index 42691d6b77..b310da5781 100644
--- a/src/widgets/statemachine/qguistatemachine.cpp
+++ b/src/widgets/statemachine/qguistatemachine.cpp
@@ -456,7 +456,7 @@ const QStateMachinePrivate::Handler qt_gui_statemachine_handler = {
     cloneEvent
 };
 
-static const QStateMachinePrivate::Handler *qt_guistatemachine_last_handler = 0;
+static const QStateMachinePrivate::Handler *qt_guistatemachine_last_handler = nullptr;
 void qRegisterGuiStateMachine()
 {
     qt_guistatemachine_last_handler = QStateMachinePrivate::handler;
diff --git a/src/widgets/styles/qcommonstyle.cpp b/src/widgets/styles/qcommonstyle.cpp
index 861dd7a54c..6b3e3679ae 100644
--- a/src/widgets/styles/qcommonstyle.cpp
+++ b/src/widgets/styles/qcommonstyle.cpp
@@ -123,7 +123,7 @@ QT_BEGIN_NAMESPACE
 
 static QWindow *qt_getWindow(const QWidget *widget)
 {
-    return widget ? widget->window()->windowHandle() : 0;
+    return widget ? widget->window()->windowHandle() : nullptr;
 }
 
 /*!
@@ -353,7 +353,7 @@ void QCommonStyle::drawPrimitive(PrimitiveElement pe, const QStyleOption *opt, Q
             p->fillRect(mid_h, opt->rect.y(), 1, bef_v - opt->rect.y(), brush);
         break; }
     case PE_FrameStatusBarItem:
-        qDrawShadeRect(p, opt->rect, opt->palette, true, 1, 0, 0);
+        qDrawShadeRect(p, opt->rect, opt->palette, true, 1, 0, nullptr);
         break;
     case PE_IndicatorHeaderArrow:
         if (const QStyleOptionHeader *header = qstyleoption_cast<const QStyleOptionHeader *>(opt)) {
@@ -450,7 +450,7 @@ void QCommonStyle::drawPrimitive(PrimitiveElement pe, const QStyleOption *opt, Q
 #endif // QT_CONFIG(tabbar)
     case PE_FrameTabWidget:
     case PE_FrameWindow:
-        qDrawWinPanel(p, opt->rect, opt->palette, false, 0);
+        qDrawWinPanel(p, opt->rect, opt->palette, false, nullptr);
         break;
     case PE_FrameLineEdit:
         proxy()->drawPrimitive(PE_Frame, opt, p, widget);
@@ -493,17 +493,17 @@ void QCommonStyle::drawPrimitive(PrimitiveElement pe, const QStyleOption *opt, Q
                 x -= 2;
             if (opt->rect.height() > 4) {
                 qDrawShadePanel(p, x, 2, 3, opt->rect.height() - 4,
-                                opt->palette, false, 1, 0);
+                                opt->palette, false, 1, nullptr);
                 qDrawShadePanel(p, x+3, 2, 3, opt->rect.height() - 4,
-                                opt->palette, false, 1, 0);
+                                opt->palette, false, 1, nullptr);
             }
         } else {
             if (opt->rect.width() > 4) {
                 int y = opt->rect.height() / 3;
                 qDrawShadePanel(p, 2, y, opt->rect.width() - 4, 3,
-                                opt->palette, false, 1, 0);
+                                opt->palette, false, 1, nullptr);
                 qDrawShadePanel(p, 2, y+3, opt->rect.width() - 4, 3,
-                                opt->palette, false, 1, 0);
+                                opt->palette, false, 1, nullptr);
             }
         }
         p->restore();
@@ -818,7 +818,7 @@ void QCommonStyle::drawPrimitive(PrimitiveElement pe, const QStyleOption *opt, Q
 
 #if QT_CONFIG(toolbutton)
 static void drawArrow(const QStyle *style, const QStyleOptionToolButton *toolbutton,
-                      const QRect &rect, QPainter *painter, const QWidget *widget = 0)
+                      const QRect &rect, QPainter *painter, const QWidget *widget = nullptr)
 {
     QStyle::PrimitiveElement pe;
     switch (toolbutton->arrowType) {
@@ -1016,7 +1016,7 @@ QSize QCommonStylePrivate::viewItemSize(const QStyleOptionViewItem *option, int
 void QCommonStylePrivate::viewItemDrawText(QPainter *p, const QStyleOptionViewItem *option, const QRect &rect) const
 {
     const QWidget *widget = option->widget;
-    const int textMargin = proxyStyle->pixelMetric(QStyle::PM_FocusFrameHMargin, 0, widget) + 1;
+    const int textMargin = proxyStyle->pixelMetric(QStyle::PM_FocusFrameHMargin, nullptr, widget) + 1;
 
     QRect textRect = rect.adjusted(textMargin, 0, -textMargin, 0); // remove width padding
     const bool wrapText = option->features & QStyleOptionViewItem::WrapText;
@@ -2931,8 +2931,8 @@ QRect QCommonStyle::subElementRect(SubElement sr, const QStyleOption *opt,
     case SE_TabBarScrollLeftButton: {
         const bool vertical = opt->rect.width() < opt->rect.height();
         const Qt::LayoutDirection ld = widget->layoutDirection();
-        const int buttonWidth = qMax(proxy()->pixelMetric(QStyle::PM_TabBarScrollButtonWidth, 0, widget), QApplication::globalStrut().width());
-        const int buttonOverlap = proxy()->pixelMetric(QStyle::PM_TabBar_ScrollButtonOverlap, 0, widget);
+        const int buttonWidth = qMax(proxy()->pixelMetric(QStyle::PM_TabBarScrollButtonWidth, nullptr, widget), QApplication::globalStrut().width());
+        const int buttonOverlap = proxy()->pixelMetric(QStyle::PM_TabBar_ScrollButtonOverlap, nullptr, widget);
 
         r = vertical ? QRect(0, opt->rect.height() - (buttonWidth * 2) + buttonOverlap, opt->rect.width(), buttonWidth)
             : QStyle::visualRect(ld, opt->rect, QRect(opt->rect.width() - (buttonWidth * 2) + buttonOverlap, 0, buttonWidth, opt->rect.height()));
@@ -2940,7 +2940,7 @@ QRect QCommonStyle::subElementRect(SubElement sr, const QStyleOption *opt,
     case SE_TabBarScrollRightButton: {
         const bool vertical = opt->rect.width() < opt->rect.height();
         const Qt::LayoutDirection ld = widget->layoutDirection();
-        const int buttonWidth = qMax(proxy()->pixelMetric(QStyle::PM_TabBarScrollButtonWidth, 0, widget), QApplication::globalStrut().width());
+        const int buttonWidth = qMax(proxy()->pixelMetric(QStyle::PM_TabBarScrollButtonWidth, nullptr, widget), QApplication::globalStrut().width());
 
         r = vertical ? QRect(0, opt->rect.height() - buttonWidth, opt->rect.width(), buttonWidth)
             : QStyle::visualRect(ld, opt->rect, QRect(opt->rect.width() - buttonWidth, 0, buttonWidth, opt->rect.height()));
@@ -3030,8 +3030,8 @@ QRect QCommonStyle::subElementRect(SubElement sr, const QStyleOption *opt,
 
         const QStyleOptionDockWidget *dwOpt
             = qstyleoption_cast<const QStyleOptionDockWidget*>(opt);
-        bool canClose = dwOpt == 0 ? true : dwOpt->closable;
-        bool canFloat = dwOpt == 0 ? false : dwOpt->floatable;
+        bool canClose = dwOpt == nullptr ? true : dwOpt->closable;
+        bool canFloat = dwOpt == nullptr ? false : dwOpt->floatable;
 
         const bool verticalTitleBar = dwOpt && dwOpt->verticalTitleBar;
 
@@ -3134,7 +3134,7 @@ QRect QCommonStyle::subElementRect(SubElement sr, const QStyleOption *opt,
                 d->viewItemLayout(vopt, &d->checkRect, &d->decorationRect, &d->displayRect, false);
                 if (d->cachedOption) {
                     delete d->cachedOption;
-                    d->cachedOption = 0;
+                    d->cachedOption = nullptr;
                 }
                 d->cachedOption = new QStyleOptionViewItem(*vopt);
             }
diff --git a/src/widgets/styles/qproxystyle.cpp b/src/widgets/styles/qproxystyle.cpp
index 5739678932..cfaa5a2011 100644
--- a/src/widgets/styles/qproxystyle.cpp
+++ b/src/widgets/styles/qproxystyle.cpp
@@ -90,7 +90,7 @@ void QProxyStylePrivate::ensureBaseStyle() const
             if (qstrcmp(baseStyle->metaObject()->className(),
                         q->metaObject()->className()) == 0) {
                 delete baseStyle;
-                baseStyle = 0;
+                baseStyle = nullptr;
             }
         }
     }
diff --git a/src/widgets/styles/qstylefactory.cpp b/src/widgets/styles/qstylefactory.cpp
index b0ce5e52cf..2c4f6f83a1 100644
--- a/src/widgets/styles/qstylefactory.cpp
+++ b/src/widgets/styles/qstylefactory.cpp
@@ -88,7 +88,7 @@ Q_GLOBAL_STATIC_WITH_ARGS(QFactoryLoader, loader,
 */
 QStyle *QStyleFactory::create(const QString& key)
 {
-    QStyle *ret = 0;
+    QStyle *ret = nullptr;
     QString style = key.toLower();
 #if QT_CONFIG(style_windows)
     if (style == QLatin1String("windows"))
diff --git a/src/widgets/styles/qstylehelper.cpp b/src/widgets/styles/qstylehelper.cpp
index 9477ca86da..61a59b03c1 100644
--- a/src/widgets/styles/qstylehelper.cpp
+++ b/src/widgets/styles/qstylehelper.cpp
@@ -132,7 +132,7 @@ bool isInstanceOf(QObject *obj, QAccessible::Role role)
 bool hasAncestor(QObject *obj, QAccessible::Role role)
 {
     bool found = false;
-    QObject *parent = obj ? obj->parent() : 0;
+    QObject *parent = obj ? obj->parent() : nullptr;
     while (parent && !found) {
         if (isInstanceOf(parent, role))
             found = true;
diff --git a/src/widgets/styles/qstyleoption.cpp b/src/widgets/styles/qstyleoption.cpp
index e5e93ecc66..1af839c841 100644
--- a/src/widgets/styles/qstyleoption.cpp
+++ b/src/widgets/styles/qstyleoption.cpp
@@ -151,7 +151,7 @@ QT_BEGIN_NAMESPACE
 
 QStyleOption::QStyleOption(int version, int type)
     : version(version), type(type), state(QStyle::State_None),
-      direction(QGuiApplication::layoutDirection()), fontMetrics(QFont()), styleObject(0)
+      direction(QGuiApplication::layoutDirection()), fontMetrics(QFont()), styleObject(nullptr)
 {
 }
 
@@ -3085,7 +3085,7 @@ QStyleOptionViewItem::QStyleOptionViewItem()
     : QStyleOption(Version, SO_ViewItem),
       displayAlignment(Qt::AlignLeft), decorationAlignment(Qt::AlignLeft),
       textElideMode(Qt::ElideMiddle), decorationPosition(Left),
-      showDecorationSelected(false), features(None), widget(0),
+      showDecorationSelected(false), features(None), widget(nullptr),
       checkState(Qt::Unchecked), viewItemPosition(QStyleOptionViewItem::Invalid)
 {
 }
@@ -3097,7 +3097,7 @@ QStyleOptionViewItem::QStyleOptionViewItem(int version)
     : QStyleOption(version, SO_ViewItem),
       displayAlignment(Qt::AlignLeft), decorationAlignment(Qt::AlignLeft),
       textElideMode(Qt::ElideMiddle), decorationPosition(Left),
-      showDecorationSelected(false), features(None), widget(0),
+      showDecorationSelected(false), features(None), widget(nullptr),
       checkState(Qt::Unchecked), viewItemPosition(QStyleOptionViewItem::Invalid)
 {
 }
diff --git a/src/widgets/styles/qstylesheetstyle.cpp b/src/widgets/styles/qstylesheetstyle.cpp
index 24a397a274..c40bbbc96c 100644
--- a/src/widgets/styles/qstylesheetstyle.cpp
+++ b/src/widgets/styles/qstylesheetstyle.cpp
@@ -133,7 +133,7 @@ public:
 };
 
 
-static QStyleSheetStyleCaches *styleSheetCaches = 0;
+static QStyleSheetStyleCaches *styleSheetCaches = nullptr;
 
 /* RECURSION_GUARD:
  * the QStyleSheetStyle is a proxy. If used with others proxy style, we may end up with something like:
@@ -144,16 +144,16 @@ static QStyleSheetStyleCaches *styleSheetCaches = 0;
  * The first instance of QStyleSheetStyle will set globalStyleSheetStyle to itself. The second one
  * will notice the globalStyleSheetStyle is not istelf and call its base style directly.
  */
-static const QStyleSheetStyle *globalStyleSheetStyle = 0;
+static const QStyleSheetStyle *globalStyleSheetStyle = nullptr;
 class QStyleSheetStyleRecursionGuard
 {
     public:
         QStyleSheetStyleRecursionGuard(const QStyleSheetStyle *that)
-            :  guarded(globalStyleSheetStyle == 0)
+            :  guarded(globalStyleSheetStyle == nullptr)
             {
                 if (guarded) globalStyleSheetStyle = that;
             }
-        ~QStyleSheetStyleRecursionGuard() { if (guarded) globalStyleSheetStyle = 0; }
+        ~QStyleSheetStyleRecursionGuard() { if (guarded) globalStyleSheetStyle = nullptr; }
         bool guarded;
 };
 #define RECURSION_GUARD(RETURN) \
@@ -371,7 +371,7 @@ struct QStyleSheetBackgroundData : public QSharedData
 
 struct QStyleSheetBorderData : public QSharedData
 {
-    QStyleSheetBorderData() : bi(0)
+    QStyleSheetBorderData() : bi(nullptr)
     {
         for (int i = 0; i < 4; i++) {
             borders[i] = 0;
@@ -379,7 +379,7 @@ struct QStyleSheetBorderData : public QSharedData
         }
     }
 
-    QStyleSheetBorderData(int *b, QBrush *c, QCss::BorderStyle *s, QSize *r) : bi(0)
+    QStyleSheetBorderData(int *b, QBrush *c, QCss::BorderStyle *s, QSize *r) : bi(nullptr)
     {
         for (int i = 0; i < 4; i++) {
             borders[i] = b[i];
@@ -396,7 +396,7 @@ struct QStyleSheetBorderData : public QSharedData
 
     const QStyleSheetBorderImageData *borderImage() const
     { return bi; }
-    bool hasBorderImage() const { return bi!=0; }
+    bool hasBorderImage() const { return bi!=nullptr; }
 
     QSharedDataPointer<QStyleSheetBorderImageData> bi;
 
@@ -413,7 +413,7 @@ struct QStyleSheetBorderData : public QSharedData
             if (!radii[i].isEmpty())
                 return false;
         }
-        if (bi != 0 && bi->pixmap.hasAlpha())
+        if (bi != nullptr && bi->pixmap.hasAlpha())
             return false;
         return true;
     }
@@ -502,7 +502,7 @@ struct QStyleSheetImageData : public QSharedData
 class QRenderRule
 {
 public:
-    QRenderRule() : features(0), hasFont(false), pal(0), b(0), bg(0), bd(0), ou(0), geo(0), p(0), img(0), clipset(0) { }
+    QRenderRule() : features(0), hasFont(false), pal(nullptr), b(nullptr), bg(nullptr), bd(nullptr), ou(nullptr), geo(nullptr), p(nullptr), img(nullptr), clipset(0) { }
     QRenderRule(const QVector<QCss::Declaration> &, const QObject *);
 
     QRect borderRect(const QRect &r) const;
@@ -538,18 +538,18 @@ public:
 
     bool hasModification() const;
 
-    bool hasPalette() const { return pal != 0; }
-    bool hasBackground() const { return bg != 0 && (!bg->pixmap.isNull() || bg->brush.style() != Qt::NoBrush); }
+    bool hasPalette() const { return pal != nullptr; }
+    bool hasBackground() const { return bg != nullptr && (!bg->pixmap.isNull() || bg->brush.style() != Qt::NoBrush); }
     bool hasGradientBackground() const { return bg && bg->brush.style() >= Qt::LinearGradientPattern
                                                    && bg->brush.style() <= Qt::ConicalGradientPattern; }
 
     bool hasNativeBorder() const {
-        return bd == 0
+        return bd == nullptr
                || (!bd->hasBorderImage() && bd->styles[0] == BorderStyle_Native);
     }
 
     bool hasNativeOutline() const {
-        return (ou == 0
+        return (ou == nullptr
                 || (!ou->hasBorderImage() && ou->styles[0] == BorderStyle_Native));
     }
 
@@ -563,14 +563,14 @@ public:
         return features & StyleFeature_BackgroundColor;
     }
 
-    bool hasBox() const { return b != 0; }
-    bool hasBorder() const { return bd != 0; }
-    bool hasOutline() const { return ou != 0; }
-    bool hasPosition() const { return p != 0; }
-    bool hasGeometry() const { return geo != 0; }
+    bool hasBox() const { return b != nullptr; }
+    bool hasBorder() const { return bd != nullptr; }
+    bool hasOutline() const { return ou != nullptr; }
+    bool hasPosition() const { return p != nullptr; }
+    bool hasGeometry() const { return geo != nullptr; }
     bool hasDrawable() const { return !hasNativeBorder() || hasBackground() || hasImage(); }
-    bool hasImage() const { return img != 0; }
-    bool hasIcon() const { return iconPtr != 0; }
+    bool hasImage() const { return img != nullptr; }
+    bool hasIcon() const { return iconPtr != nullptr; }
 
     QSize minimumContentsSize() const
     { return geo ? QSize(geo->minWidth, geo->minHeight) : QSize(0, 0); }
@@ -910,7 +910,7 @@ static QStyle::StandardPixmap subControlIcon(int pe)
 }
 
 QRenderRule::QRenderRule(const QVector<Declaration> &declarations, const QObject *object)
-: features(0), hasFont(false), pal(0), b(0), bg(0), bd(0), ou(0), geo(0), p(0), img(0), clipset(0)
+: features(0), hasFont(false), pal(nullptr), b(nullptr), bg(nullptr), bd(nullptr), ou(nullptr), geo(nullptr), p(nullptr), img(nullptr), clipset(0)
 {
     QPalette palette = QGuiApplication::palette(); // ###: ideally widget's palette
     ValueExtractor v(declarations, palette);
@@ -1134,11 +1134,11 @@ QSize QRenderRule::boxSize(const QSize &cs, int flags) const
 
 void QRenderRule::fixupBorder(int nativeWidth)
 {
-    if (bd == 0)
+    if (bd == nullptr)
         return;
 
     if (!bd->hasBorderImage() || bd->bi->pixmap.isNull()) {
-        bd->bi = 0;
+        bd->bi = nullptr;
         // ignore the color, border of edges that have none border-style
         QBrush color = pal ? pal->foreground : QBrush();
         const bool hasRadius = bd->radii[0].isValid() || bd->radii[1].isValid()
@@ -1515,7 +1515,7 @@ public:
         do {
             result += QString::fromLatin1(metaObject->className()).replace(QLatin1Char(':'), QLatin1Char('-'));
             metaObject = metaObject->superClass();
-        } while (metaObject != 0);
+        } while (metaObject != nullptr);
         return result;
     }
     QString attribute(NodePtr node, const QString& name) const override
@@ -1539,7 +1539,7 @@ public:
                 return className;
             } else if (name == QLatin1String("style")) {
                 QWidget *w = qobject_cast<QWidget *>(obj);
-                QStyleSheetStyle *proxy = w ? qt_styleSheet(w->style()) : 0;
+                QStyleSheetStyle *proxy = w ? qt_styleSheet(w->style()) : nullptr;
                 if (proxy) {
                     QString styleName = QString::fromLatin1(proxy->baseStyle()->metaObject()->className());
                     cache[name] = styleName;
@@ -1575,7 +1575,7 @@ public:
             if (uc == e && !*c)
                 return true;
             metaObject = metaObject->superClass();
-        } while (metaObject != 0);
+        } while (metaObject != nullptr);
         return false;
     }
     bool hasAttributes(NodePtr) const override
@@ -1583,11 +1583,11 @@ public:
     QStringList nodeIds(NodePtr node) const override
     { return isNullNode(node) ? QStringList() : QStringList(OBJECT_PTR(node)->objectName()); }
     bool isNullNode(NodePtr node) const override
-    { return node.ptr == 0; }
+    { return node.ptr == nullptr; }
     NodePtr parentNode(NodePtr node) const override
-    { NodePtr n; n.ptr = isNullNode(node) ? 0 : parentObject(OBJECT_PTR(node)); return n; }
+    { NodePtr n; n.ptr = isNullNode(node) ? nullptr : parentObject(OBJECT_PTR(node)); return n; }
     NodePtr previousSiblingNode(NodePtr) const override
-    { NodePtr n; n.ptr = 0; return n; }
+    { NodePtr n; n.ptr = nullptr; return n; }
     NodePtr duplicateNode(NodePtr node) const override
     { return node; }
     void freeNode(NodePtr) const override
@@ -1700,22 +1700,22 @@ int QStyleSheetStyle::nativeFrameWidth(const QWidget *w)
 
 #if QT_CONFIG(spinbox)
     if (qobject_cast<const QAbstractSpinBox *>(w))
-        return base->pixelMetric(QStyle::PM_SpinBoxFrameWidth, 0, w);
+        return base->pixelMetric(QStyle::PM_SpinBoxFrameWidth, nullptr, w);
 #endif
 
 #if QT_CONFIG(combobox)
     if (qobject_cast<const QComboBox *>(w))
-        return base->pixelMetric(QStyle::PM_ComboBoxFrameWidth, 0, w);
+        return base->pixelMetric(QStyle::PM_ComboBoxFrameWidth, nullptr, w);
 #endif
 
 #if QT_CONFIG(menu)
     if (qobject_cast<const QMenu *>(w))
-        return base->pixelMetric(QStyle::PM_MenuPanelWidth, 0, w);
+        return base->pixelMetric(QStyle::PM_MenuPanelWidth, nullptr, w);
 #endif
 
 #if QT_CONFIG(menubar)
     if (qobject_cast<const QMenuBar *>(w))
-        return base->pixelMetric(QStyle::PM_MenuBarPanelWidth, 0, w);
+        return base->pixelMetric(QStyle::PM_MenuBarPanelWidth, nullptr, w);
 #endif
 #ifndef QT_NO_FRAME
     if (const QFrame *frame = qobject_cast<const QFrame *>(w)) {
@@ -1725,9 +1725,9 @@ int QStyleSheetStyle::nativeFrameWidth(const QWidget *w)
 #endif
 
     if (qstrcmp(w->metaObject()->className(), "QTipLabel") == 0)
-        return base->pixelMetric(QStyle::PM_ToolTipLabelFrameWidth, 0, w);
+        return base->pixelMetric(QStyle::PM_ToolTipLabelFrameWidth, nullptr, w);
 
-    return base->pixelMetric(QStyle::PM_DefaultFrameWidth, 0, w);
+    return base->pixelMetric(QStyle::PM_DefaultFrameWidth, nullptr, w);
 }
 
 static quint64 pseudoClass(QStyle::State state)
@@ -2243,21 +2243,21 @@ QSize QStyleSheetStyle::defaultSize(const QWidget *w, QSize sz, const QRect& rec
     case PseudoElement_Indicator:
     case PseudoElement_MenuCheckMark:
         if (sz.width() == -1)
-            sz.setWidth(base->pixelMetric(PM_IndicatorWidth, 0, w));
+            sz.setWidth(base->pixelMetric(PM_IndicatorWidth, nullptr, w));
         if (sz.height() == -1)
-            sz.setHeight(base->pixelMetric(PM_IndicatorHeight, 0, w));
+            sz.setHeight(base->pixelMetric(PM_IndicatorHeight, nullptr, w));
         break;
 
     case PseudoElement_ExclusiveIndicator:
     case PseudoElement_GroupBoxIndicator:
         if (sz.width() == -1)
-            sz.setWidth(base->pixelMetric(PM_ExclusiveIndicatorWidth, 0, w));
+            sz.setWidth(base->pixelMetric(PM_ExclusiveIndicatorWidth, nullptr, w));
         if (sz.height() == -1)
-            sz.setHeight(base->pixelMetric(PM_ExclusiveIndicatorHeight, 0, w));
+            sz.setHeight(base->pixelMetric(PM_ExclusiveIndicatorHeight, nullptr, w));
         break;
 
     case PseudoElement_PushButtonMenuIndicator: {
-        int pm = base->pixelMetric(PM_MenuButtonIndicator, 0, w);
+        int pm = base->pixelMetric(PM_MenuButtonIndicator, nullptr, w);
         if (sz.width() == -1)
             sz.setWidth(pm);
         if (sz.height() == -1)
@@ -2291,12 +2291,12 @@ QSize QStyleSheetStyle::defaultSize(const QWidget *w, QSize sz, const QRect& rec
 
     case PseudoElement_ToolButtonMenu:
         if (sz.width() == -1)
-            sz.setWidth(base->pixelMetric(PM_MenuButtonIndicator, 0, w));
+            sz.setWidth(base->pixelMetric(PM_MenuButtonIndicator, nullptr, w));
         break;
 
     case PseudoElement_HeaderViewUpArrow:
     case PseudoElement_HeaderViewDownArrow: {
-        int pm = base->pixelMetric(PM_HeaderMargin, 0, w);
+        int pm = base->pixelMetric(PM_HeaderMargin, nullptr, w);
         if (sz.width() == -1)
             sz.setWidth(pm);
         if (sz.height() == 1)
@@ -2309,7 +2309,7 @@ QSize QStyleSheetStyle::defaultSize(const QWidget *w, QSize sz, const QRect& rec
     case PseudoElement_ScrollBarAddLine:
     case PseudoElement_ScrollBarSubLine:
     case PseudoElement_ScrollBarSlider: {
-        int pm = pixelMetric(QStyle::PM_ScrollBarExtent, 0, w);
+        int pm = pixelMetric(QStyle::PM_ScrollBarExtent, nullptr, w);
         if (sz.width() == -1)
             sz.setWidth(pm);
         if (sz.height() == -1)
@@ -2319,7 +2319,7 @@ QSize QStyleSheetStyle::defaultSize(const QWidget *w, QSize sz, const QRect& rec
 
     case PseudoElement_DockWidgetCloseButton:
     case PseudoElement_DockWidgetFloatButton: {
-        int iconSize = pixelMetric(PM_SmallIconSize, 0, w);
+        int iconSize = pixelMetric(PM_SmallIconSize, nullptr, w);
         return QSize(iconSize, iconSize);
                                               }
 
@@ -2956,7 +2956,7 @@ void QStyleSheetStyle::unpolish(QWidget *w)
     setGeometry(w);
     w->setAttribute(Qt::WA_StyleSheetTarget, false);
     w->setAttribute(Qt::WA_StyleSheet, false);
-    QObject::disconnect(w, 0, this, 0);
+    QObject::disconnect(w, nullptr, this, nullptr);
 #if QT_CONFIG(scrollarea)
     if (QAbstractScrollArea *sa = qobject_cast<QAbstractScrollArea *>(w)) {
         QObject::disconnect(sa->horizontalScrollBar(), SIGNAL(valueChanged(int)),
@@ -3395,7 +3395,7 @@ void QStyleSheetStyle::drawComplexControl(ComplexControl cc, const QStyleOptionC
                     tb->icon.paint(p, ir);
                 } else {
                     int iconSize = pixelMetric(PM_SmallIconSize, tb, w);
-                    pm = standardIcon(SP_TitleBarMenuButton, 0, w).pixmap(iconSize, iconSize);
+                    pm = standardIcon(SP_TitleBarMenuButton, nullptr, w).pixmap(iconSize, iconSize);
                     drawItemPixmap(p, ir, Qt::AlignCenter, pm);
                 }
             }
@@ -3407,9 +3407,9 @@ void QStyleSheetStyle::drawComplexControl(ComplexControl cc, const QStyleOptionC
 
                 QSize sz = subSubRule.contentsRect(ir).size();
                 if ((tb->titleBarFlags & Qt::WindowType_Mask) == Qt::Tool)
-                    pm = standardIcon(SP_DockWidgetCloseButton, 0, w).pixmap(sz);
+                    pm = standardIcon(SP_DockWidgetCloseButton, nullptr, w).pixmap(sz);
                 else
-                    pm = standardIcon(SP_TitleBarCloseButton, 0, w).pixmap(sz);
+                    pm = standardIcon(SP_TitleBarCloseButton, nullptr, w).pixmap(sz);
                 drawItemPixmap(p, ir, Qt::AlignCenter, pm);
             }
 
@@ -3430,7 +3430,7 @@ void QStyleSheetStyle::drawComplexControl(ComplexControl cc, const QStyleOptionC
                     continue;
                 QRenderRule subSubRule = renderRule(w, opt, pe);
                 subSubRule.drawRule(p, ir);
-                pm = standardIcon(subControlIcon(pe), 0, w).pixmap(subSubRule.contentsRect(ir).size());
+                pm = standardIcon(subControlIcon(pe), nullptr, w).pixmap(subSubRule.contentsRect(ir).size());
                 drawItemPixmap(p, ir, Qt::AlignCenter, pm);
             }
 
@@ -4280,7 +4280,7 @@ void QStyleSheetStyle::drawControl(ControlElement ce, const QStyleOption *opt, Q
 
     if (pe1 != PseudoElement_None) {
         QRenderRule subRule = renderRule(w, opt, pe1);
-        if (subRule.bg != 0 || subRule.hasDrawable()) {
+        if (subRule.bg != nullptr || subRule.hasDrawable()) {
             //We test subRule.bg directly because hasBackground() would return false for background:none.
             //But we still don't want the default drawning in that case (example for QScrollBar::add-page) (task 198926)
             subRule.drawRule(p, opt->rect);
@@ -5088,7 +5088,7 @@ QSize QStyleSheetStyle::sizeFromContents(ContentsType ct, const QStyleOption *op
     case CT_GroupBox:
     case CT_LineEdit:
 #if QT_CONFIG(spinbox)
-        if (qobject_cast<QAbstractSpinBox *>(w ? w->parentWidget() : 0))
+        if (qobject_cast<QAbstractSpinBox *>(w ? w->parentWidget() : nullptr))
             return csz; // we only care about the size hint of the line edit
 #endif
         if (rule.hasBox() || !rule.hasNativeBorder()) {
@@ -5729,7 +5729,7 @@ QRect QStyleSheetStyle::subControlRect(ComplexControl cc, const QStyleOptionComp
             QRenderRule subRule = renderRule(w, opt, PseudoElement_SliderGroove);
             if (!subRule.hasDrawable())
                 break;
-            subRule.img = 0;
+            subRule.img = nullptr;
             QRect gr = positionRect(w, rule, subRule, PseudoElement_SliderGroove, opt->rect, opt->direction);
             switch (sc) {
             case SC_SliderGroove:
@@ -5739,8 +5739,8 @@ QRect QStyleSheetStyle::subControlRect(ComplexControl cc, const QStyleOptionComp
                 QRect cr = subRule.contentsRect(gr);
                 QRenderRule subRule2 = renderRule(w, opt, PseudoElement_SliderHandle);
                 int len = horizontal ? subRule2.size().width() : subRule2.size().height();
-                subRule2.img = 0;
-                subRule2.geo = 0;
+                subRule2.img = nullptr;
+                subRule2.geo = nullptr;
                 cr = positionRect(w, subRule2, PseudoElement_SliderHandle, cr, opt->direction);
                 int thickness = horizontal ? cr.height() : cr.width();
                 int sliderPos = sliderPositionFromValue(slider->minimum, slider->maximum, slider->sliderPosition,
@@ -5848,7 +5848,7 @@ QRect QStyleSheetStyle::subElementRect(SubElement se, const QStyleOption *opt, c
             QRect ir = subElementRect(isRadio ? SE_RadioButtonIndicator : SE_CheckBoxIndicator,
                                       opt, w);
             ir = visualRect(opt->direction, opt->rect, ir);
-            int spacing = pixelMetric(isRadio ? PM_RadioButtonLabelSpacing : PM_CheckBoxLabelSpacing, 0, w);
+            int spacing = pixelMetric(isRadio ? PM_RadioButtonLabelSpacing : PM_CheckBoxLabelSpacing, nullptr, w);
             QRect cr = rule.contentsRect(opt->rect);
             ir.setRect(ir.left() + ir.width() + spacing, cr.y(),
                        cr.width() - ir.width() - spacing, cr.height());
diff --git a/src/widgets/util/qcolormap.cpp b/src/widgets/util/qcolormap.cpp
index 6dacc97261..57e61690e9 100644
--- a/src/widgets/util/qcolormap.cpp
+++ b/src/widgets/util/qcolormap.cpp
@@ -59,7 +59,7 @@ public:
     int numcolors;
 };
 
-static QColormapPrivate *screenMap = 0;
+static QColormapPrivate *screenMap = nullptr;
 
 void QColormap::initialize()
 {
@@ -83,7 +83,7 @@ void QColormap::initialize()
 void QColormap::cleanup()
 {
     delete screenMap;
-    screenMap = 0;
+    screenMap = nullptr;
 }
 
 QColormap QColormap::instance(int /*screen*/)
diff --git a/src/widgets/util/qcompleter.cpp b/src/widgets/util/qcompleter.cpp
index 3c0271e7c2..72fa557790 100644
--- a/src/widgets/util/qcompleter.cpp
+++ b/src/widgets/util/qcompleter.cpp
@@ -1262,7 +1262,7 @@ Qt::MatchFlags QCompleter::filterMode() const
 void QCompleter::setPopup(QAbstractItemView *popup)
 {
     Q_D(QCompleter);
-    Q_ASSERT(popup != 0);
+    Q_ASSERT(popup != nullptr);
     if (d->popup) {
         QObject::disconnect(d->popup->selectionModel(), nullptr, this, nullptr);
         QObject::disconnect(d->popup, nullptr, this, nullptr);
diff --git a/src/widgets/util/qflickgesture.cpp b/src/widgets/util/qflickgesture.cpp
index 03df937938..064be873b9 100644
--- a/src/widgets/util/qflickgesture.cpp
+++ b/src/widgets/util/qflickgesture.cpp
@@ -114,19 +114,19 @@ static QMouseEvent *copyMouseEvent(QEvent *e)
     }
 #endif // QT_CONFIG(graphicsview)
     default:
-        return 0;
+        return nullptr;
     }
 }
 
 class PressDelayHandler : public QObject
 {
 private:
-    PressDelayHandler(QObject *parent = 0)
+    PressDelayHandler(QObject *parent = nullptr)
         : QObject(parent)
         , pressDelayTimer(0)
         , sendingEvent(false)
         , mouseButton(Qt::NoButton)
-        , mouseTarget(0)
+        , mouseTarget(nullptr)
         , mouseEventSource(Qt::MouseEventNotSynthesized)
     { }
 
@@ -138,7 +138,7 @@ public:
 
     static PressDelayHandler *instance()
     {
-        static PressDelayHandler *inst = 0;
+        static PressDelayHandler *inst = nullptr;
         if (!inst)
             inst = new PressDelayHandler(QCoreApplication::instance());
         return inst;
@@ -192,10 +192,10 @@ public:
             result = true; // consume this event
         } else if (mouseTarget && scrollerIsActive) {
             // we grabbed the mouse expicitly when the scroller became active, so undo that now
-            sendMouseEvent(0, UngrabMouseBefore);
+            sendMouseEvent(nullptr, UngrabMouseBefore);
         }
-        pressDelayEvent.reset(0);
-        mouseTarget = 0;
+        pressDelayEvent.reset(nullptr);
+        mouseTarget = nullptr;
         return result;
     }
 
@@ -208,9 +208,9 @@ public:
                 killTimer(pressDelayTimer);
                 pressDelayTimer = 0;
             }
-            pressDelayEvent.reset(0);
+            pressDelayEvent.reset(nullptr);
         }
-        mouseTarget = 0;
+        mouseTarget = nullptr;
     }
 
     void scrollerBecameActive()
@@ -222,8 +222,8 @@ public:
                 killTimer(pressDelayTimer);
                 pressDelayTimer = 0;
             }
-            pressDelayEvent.reset(0);
-            mouseTarget = 0;
+            pressDelayEvent.reset(nullptr);
+            mouseTarget = nullptr;
         } else if (mouseTarget) {
             // we did send a press, so we need to fake a release now
 
@@ -261,7 +261,7 @@ protected:
                 qFGDebug() << "QFG: timer event: re-sending mouse press to " << mouseTarget;
                 sendMouseEvent(pressDelayEvent.data(), UngrabMouseBefore);
             }
-            pressDelayEvent.reset(0);
+            pressDelayEvent.reset(nullptr);
 
             if (pressDelayTimer) {
                 killTimer(pressDelayTimer);
@@ -276,7 +276,7 @@ protected:
             sendingEvent = true;
 
 #if QT_CONFIG(graphicsview)
-            QGraphicsItem *grabber = 0;
+            QGraphicsItem *grabber = nullptr;
             if (mouseTarget->parentWidget()) {
                 if (QGraphicsView *gv = qobject_cast<QGraphicsView *>(mouseTarget->parentWidget())) {
                     if (gv->scene())
@@ -350,7 +350,7 @@ QFlickGesture::QFlickGesture(QObject *receiver, Qt::MouseButton button, QObject
 {
     d_func()->q_ptr = this;
     d_func()->receiver = receiver;
-    d_func()->receiverScroller = (receiver && QScroller::hasScroller(receiver)) ? QScroller::scroller(receiver) : 0;
+    d_func()->receiverScroller = (receiver && QScroller::hasScroller(receiver)) ? QScroller::scroller(receiver) : nullptr;
     d_func()->button = button;
 }
 
@@ -358,7 +358,7 @@ QFlickGesture::~QFlickGesture()
 { }
 
 QFlickGesturePrivate::QFlickGesturePrivate()
-    : receiverScroller(0), button(Qt::NoButton), macIgnoreWheel(false)
+    : receiverScroller(nullptr), button(Qt::NoButton), macIgnoreWheel(false)
 { }
 
 
@@ -420,11 +420,11 @@ QGestureRecognizer::Result QFlickGestureRecognizer::recognize(QGesture *state,
         return Ignore;
     }
 
-    const QMouseEvent *me = 0;
+    const QMouseEvent *me = nullptr;
 #if QT_CONFIG(graphicsview)
-    const QGraphicsSceneMouseEvent *gsme = 0;
+    const QGraphicsSceneMouseEvent *gsme = nullptr;
 #endif
-    const QTouchEvent *te = 0;
+    const QTouchEvent *te = nullptr;
     QPoint globalPos;
 
     // qFGDebug() << "FlickGesture "<<state<<"watched:"<<watched<<"receiver"<<d->receiver<<"event"<<event->type()<<"button"<<button;
diff --git a/src/widgets/util/qscroller.cpp b/src/widgets/util/qscroller.cpp
index df05bbf71c..fec373d45c 100644
--- a/src/widgets/util/qscroller.cpp
+++ b/src/widgets/util/qscroller.cpp
@@ -300,7 +300,7 @@ QScroller *QScroller::scroller(QObject *target)
 {
     if (!target) {
         qWarning("QScroller::scroller() was called with a null target.");
-        return 0;
+        return nullptr;
     }
 
     if (qt_allScrollers()->contains(target))
@@ -476,7 +476,7 @@ void QScroller::ungrabGesture(QObject *target)
 
     QGestureRecognizer::unregisterRecognizer(sp->recognizerType);
     // do not delete the recognizer. The QGestureManager is doing this.
-    sp->recognizer = 0;
+    sp->recognizer = nullptr;
 }
 
 #endif // QT_NO_GESTURES
@@ -502,7 +502,7 @@ QScroller::~QScroller()
 #ifndef QT_NO_GESTURES
     QGestureRecognizer::unregisterRecognizer(d->recognizerType);
     // do not delete the recognizer. The QGestureManager is doing this.
-    d->recognizer = 0;
+    d->recognizer = nullptr;
 #endif
     qt_allScrollers()->remove(d->target);
     qt_activeScrollers()->removeOne(this);
@@ -879,7 +879,7 @@ void QScroller::setSnapPositionsY(qreal first, qreal interval)
 QScrollerPrivate::QScrollerPrivate(QScroller *q, QObject *_target)
     : target(_target)
 #ifndef QT_NO_GESTURES
-    , recognizer(0)
+    , recognizer(nullptr)
     , recognizerType(Qt::CustomGesture)
 #endif
     , state(QScroller::Inactive)
@@ -900,7 +900,7 @@ QScrollerPrivate::QScrollerPrivate(QScroller *q, QObject *_target)
 
 void QScrollerPrivate::init()
 {
-    setDpiFromWidget(0);
+    setDpiFromWidget(nullptr);
     monotonicTimer.start();
 }
 
diff --git a/src/widgets/util/qscrollerproperties.cpp b/src/widgets/util/qscrollerproperties.cpp
index df6b899fe4..0306f54faa 100644
--- a/src/widgets/util/qscrollerproperties.cpp
+++ b/src/widgets/util/qscrollerproperties.cpp
@@ -46,8 +46,8 @@
 
 QT_BEGIN_NAMESPACE
 
-static QScrollerPropertiesPrivate *userDefaults = 0;
-static QScrollerPropertiesPrivate *systemDefaults = 0;
+static QScrollerPropertiesPrivate *userDefaults = nullptr;
+static QScrollerPropertiesPrivate *systemDefaults = nullptr;
 
 QScrollerPropertiesPrivate *QScrollerPropertiesPrivate::defaults()
 {
@@ -200,7 +200,7 @@ void QScrollerProperties::setDefaultScrollerProperties(const QScrollerProperties
 void QScrollerProperties::unsetDefaultScrollerProperties()
 {
     delete userDefaults;
-    userDefaults = 0;
+    userDefaults = nullptr;
 }
 
 /*!
diff --git a/src/widgets/util/qsystemtrayicon.cpp b/src/widgets/util/qsystemtrayicon.cpp
index ae81cc5661..ee52139913 100644
--- a/src/widgets/util/qsystemtrayicon.cpp
+++ b/src/widgets/util/qsystemtrayicon.cpp
@@ -453,7 +453,7 @@ void QSystemTrayIconPrivate::_q_emitActivated(QPlatformSystemTrayIcon::Activatio
 }
 
 //////////////////////////////////////////////////////////////////////
-static QBalloonTip *theSolitaryBalloonTip = 0;
+static QBalloonTip *theSolitaryBalloonTip = nullptr;
 
 void QBalloonTip::showBalloon(const QIcon &icon, const QString &title,
                               const QString &message, QSystemTrayIcon *trayIcon,
@@ -475,7 +475,7 @@ void QBalloonTip::hideBalloon()
         return;
     theSolitaryBalloonTip->hide();
     delete theSolitaryBalloonTip;
-    theSolitaryBalloonTip = 0;
+    theSolitaryBalloonTip = nullptr;
 }
 
 void QBalloonTip::updateBalloonPosition(const QPoint& pos)
@@ -493,7 +493,7 @@ bool QBalloonTip::isBalloonVisible()
 
 QBalloonTip::QBalloonTip(const QIcon &icon, const QString &title,
                          const QString &message, QSystemTrayIcon *ti)
-    : QWidget(0, Qt::ToolTip),
+    : QWidget(nullptr, Qt::ToolTip),
       trayIcon(ti),
       timerId(-1),
       showArrow(true)
@@ -583,7 +583,7 @@ QBalloonTip::QBalloonTip(const QIcon &icon, const QString &title,
 
 QBalloonTip::~QBalloonTip()
 {
-    theSolitaryBalloonTip = 0;
+    theSolitaryBalloonTip = nullptr;
 }
 
 void QBalloonTip::paintEvent(QPaintEvent *)
diff --git a/src/widgets/util/qsystemtrayicon_x11.cpp b/src/widgets/util/qsystemtrayicon_x11.cpp
index 0c7bb94a91..86c11f98ed 100644
--- a/src/widgets/util/qsystemtrayicon_x11.cpp
+++ b/src/widgets/util/qsystemtrayicon_x11.cpp
@@ -97,7 +97,7 @@ private:
 };
 
 QSystemTrayIconSys::QSystemTrayIconSys(QSystemTrayIcon *qIn)
-    : QWidget(0, Qt::Window | Qt::FramelessWindowHint | Qt::BypassWindowManagerHint)
+    : QWidget(nullptr, Qt::Window | Qt::FramelessWindowHint | Qt::BypassWindowManagerHint)
     , q(qIn)
 {
     setObjectName(QStringLiteral("QSystemTrayIconSys"));
@@ -218,7 +218,7 @@ private:
 ////////////////////////////////////////////////////////////////////////////
 
 QSystemTrayIconPrivate::QSystemTrayIconPrivate()
-    : sys(0),
+    : sys(nullptr),
       qpa_sys(QGuiApplicationPrivate::platformTheme()->createPlatformSystemTrayIcon()),
       visible(false),
       trayWatcher(nullptr)
diff --git a/src/widgets/util/qundogroup.cpp b/src/widgets/util/qundogroup.cpp
index 9bd63d4232..ae439743bc 100644
--- a/src/widgets/util/qundogroup.cpp
+++ b/src/widgets/util/qundogroup.cpp
@@ -47,7 +47,7 @@ class QUndoGroupPrivate : public QObjectPrivate
 {
     Q_DECLARE_PUBLIC(QUndoGroup)
 public:
-    QUndoGroupPrivate() : active(0) {}
+    QUndoGroupPrivate() : active(nullptr) {}
 
     QUndoStack *active;
     QList<QUndoStack*> stack_list;
@@ -113,7 +113,7 @@ QUndoGroup::~QUndoGroup()
     QList<QUndoStack *>::iterator it = d->stack_list.begin();
     QList<QUndoStack *>::iterator end = d->stack_list.end();
     while (it != end) {
-        (*it)->d_func()->group = 0;
+        (*it)->d_func()->group = nullptr;
         ++it;
     }
 }
@@ -154,8 +154,8 @@ void QUndoGroup::removeStack(QUndoStack *stack)
     if (d->stack_list.removeAll(stack) == 0)
         return;
     if (stack == d->active)
-        setActiveStack(0);
-    stack->d_func()->group = 0;
+        setActiveStack(nullptr);
+    stack->d_func()->group = nullptr;
 }
 
 /*!
@@ -190,7 +190,7 @@ void QUndoGroup::setActiveStack(QUndoStack *stack)
     if (d->active == stack)
         return;
 
-    if (d->active != 0) {
+    if (d->active != nullptr) {
         disconnect(d->active, SIGNAL(canUndoChanged(bool)),
                     this, SIGNAL(canUndoChanged(bool)));
         disconnect(d->active, SIGNAL(undoTextChanged(QString)),
@@ -207,7 +207,7 @@ void QUndoGroup::setActiveStack(QUndoStack *stack)
 
     d->active = stack;
 
-    if (d->active == 0) {
+    if (d->active == nullptr) {
         emit canUndoChanged(false);
         emit undoTextChanged(QString());
         emit canRedoChanged(false);
@@ -265,7 +265,7 @@ QUndoStack *QUndoGroup::activeStack() const
 void QUndoGroup::undo()
 {
     Q_D(QUndoGroup);
-    if (d->active != 0)
+    if (d->active != nullptr)
         d->active->undo();
 }
 
@@ -282,7 +282,7 @@ void QUndoGroup::undo()
 void QUndoGroup::redo()
 {
     Q_D(QUndoGroup);
-    if (d->active != 0)
+    if (d->active != nullptr)
         d->active->redo();
 }
 
@@ -298,7 +298,7 @@ void QUndoGroup::redo()
 bool QUndoGroup::canUndo() const
 {
     Q_D(const QUndoGroup);
-    return d->active != 0 && d->active->canUndo();
+    return d->active != nullptr && d->active->canUndo();
 }
 
 /*!
@@ -313,7 +313,7 @@ bool QUndoGroup::canUndo() const
 bool QUndoGroup::canRedo() const
 {
     Q_D(const QUndoGroup);
-    return d->active != 0 && d->active->canRedo();
+    return d->active != nullptr && d->active->canRedo();
 }
 
 /*!
@@ -328,7 +328,7 @@ bool QUndoGroup::canRedo() const
 QString QUndoGroup::undoText() const
 {
     Q_D(const QUndoGroup);
-    return d->active == 0 ? QString() : d->active->undoText();
+    return d->active == nullptr ? QString() : d->active->undoText();
 }
 
 /*!
@@ -343,7 +343,7 @@ QString QUndoGroup::undoText() const
 QString QUndoGroup::redoText() const
 {
     Q_D(const QUndoGroup);
-    return d->active == 0 ? QString() : d->active->redoText();
+    return d->active == nullptr ? QString() : d->active->redoText();
 }
 
 /*!
@@ -358,7 +358,7 @@ QString QUndoGroup::redoText() const
 bool QUndoGroup::isClean() const
 {
     Q_D(const QUndoGroup);
-    return d->active == 0 || d->active->isClean();
+    return d->active == nullptr || d->active->isClean();
 }
 
 #ifndef QT_NO_ACTION
diff --git a/src/widgets/util/qundostack.cpp b/src/widgets/util/qundostack.cpp
index 8788c42252..f188b8298a 100644
--- a/src/widgets/util/qundostack.cpp
+++ b/src/widgets/util/qundostack.cpp
@@ -128,7 +128,7 @@ QUndoCommand::QUndoCommand(const QString &text, QUndoCommand *parent)
 QUndoCommand::QUndoCommand(QUndoCommand *parent)
 {
     d = new QUndoCommandPrivate;
-    if (parent != 0)
+    if (parent != nullptr)
         parent->d->child_list.append(this);
 }
 
@@ -336,7 +336,7 @@ int QUndoCommand::childCount() const
 const QUndoCommand *QUndoCommand::child(int index) const
 {
     if (index < 0 || index >= d->child_list.count())
-        return 0;
+        return nullptr;
     return d->child_list.at(index);
 }
 
@@ -559,7 +559,7 @@ QUndoStack::~QUndoStack()
 {
 #if QT_CONFIG(undogroup)
     Q_D(QUndoStack);
-    if (d->group != 0)
+    if (d->group != nullptr)
         d->group->removeStack(this);
 #endif
     clear();
@@ -640,7 +640,7 @@ void QUndoStack::push(QUndoCommand *cmd)
 
     bool macro = !d->macro_stack.isEmpty();
 
-    QUndoCommand *cur = 0;
+    QUndoCommand *cur = nullptr;
     if (macro) {
         QUndoCommand *macro_cmd = d->macro_stack.constLast();
         if (!macro_cmd->d->child_list.isEmpty())
@@ -654,7 +654,7 @@ void QUndoStack::push(QUndoCommand *cmd)
             d->clean_index = -1; // we've deleted the clean state
     }
 
-    bool try_merge = cur != 0
+    bool try_merge = cur != nullptr
                         && cur->id() != -1
                         && cur->id() == cmd->id()
                         && (macro || d->index != d->clean_index);
@@ -1225,7 +1225,7 @@ const QUndoCommand *QUndoStack::command(int index) const
     Q_D(const QUndoStack);
 
     if (index < 0 || index >= d->command_list.count())
-        return 0;
+        return nullptr;
     return d->command_list.at(index);
 }
 
@@ -1305,11 +1305,11 @@ void QUndoStack::setActive(bool active)
 #else
     Q_D(QUndoStack);
 
-    if (d->group != 0) {
+    if (d->group != nullptr) {
         if (active)
             d->group->setActiveStack(this);
         else if (d->group->activeStack() == this)
-            d->group->setActiveStack(0);
+            d->group->setActiveStack(nullptr);
     }
 #endif
 }
@@ -1320,7 +1320,7 @@ bool QUndoStack::isActive() const
     return true;
 #else
     Q_D(const QUndoStack);
-    return d->group == 0 || d->group->activeStack() == this;
+    return d->group == nullptr || d->group->activeStack() == this;
 #endif
 }
 
diff --git a/src/widgets/util/qundoview.cpp b/src/widgets/util/qundoview.cpp
index f59d87fb9d..9ca83a1da2 100644
--- a/src/widgets/util/qundoview.cpp
+++ b/src/widgets/util/qundoview.cpp
@@ -54,7 +54,7 @@ class QUndoModel : public QAbstractItemModel
 {
     Q_OBJECT
 public:
-    QUndoModel(QObject *parent = 0);
+    QUndoModel(QObject *parent = nullptr);
 
     QUndoStack *stack() const;
 
@@ -92,7 +92,7 @@ private:
 QUndoModel::QUndoModel(QObject *parent)
     : QAbstractItemModel(parent)
 {
-    m_stack = 0;
+    m_stack = nullptr;
     m_sel_model = new QItemSelectionModel(this, this);
     connect(m_sel_model, SIGNAL(currentChanged(QModelIndex,QModelIndex)),
             this, SLOT(setStackCurrentIndex(QModelIndex)));
@@ -114,13 +114,13 @@ void QUndoModel::setStack(QUndoStack *stack)
     if (m_stack == stack)
         return;
 
-    if (m_stack != 0) {
+    if (m_stack != nullptr) {
         disconnect(m_stack, SIGNAL(cleanChanged(bool)), this, SLOT(stackChanged()));
         disconnect(m_stack, SIGNAL(indexChanged(int)), this, SLOT(stackChanged()));
         disconnect(m_stack, SIGNAL(destroyed(QObject*)), this, SLOT(stackDestroyed(QObject*)));
     }
     m_stack = stack;
-    if (m_stack != 0) {
+    if (m_stack != nullptr) {
         connect(m_stack, SIGNAL(cleanChanged(bool)), this, SLOT(stackChanged()));
         connect(m_stack, SIGNAL(indexChanged(int)), this, SLOT(stackChanged()));
         connect(m_stack, SIGNAL(destroyed(QObject*)), this, SLOT(stackDestroyed(QObject*)));
@@ -133,7 +133,7 @@ void QUndoModel::stackDestroyed(QObject *obj)
 {
     if (obj != m_stack)
         return;
-    m_stack = 0;
+    m_stack = nullptr;
 
     stackChanged();
 }
@@ -147,7 +147,7 @@ void QUndoModel::stackChanged()
 
 void QUndoModel::setStackCurrentIndex(const QModelIndex &index)
 {
-    if (m_stack == 0)
+    if (m_stack == nullptr)
         return;
 
     if (index == selectedIndex())
@@ -161,12 +161,12 @@ void QUndoModel::setStackCurrentIndex(const QModelIndex &index)
 
 QModelIndex QUndoModel::selectedIndex() const
 {
-    return m_stack == 0 ? QModelIndex() : createIndex(m_stack->index(), 0);
+    return m_stack == nullptr ? QModelIndex() : createIndex(m_stack->index(), 0);
 }
 
 QModelIndex QUndoModel::index(int row, int column, const QModelIndex &parent) const
 {
-    if (m_stack == 0)
+    if (m_stack == nullptr)
         return QModelIndex();
 
     if (parent.isValid())
@@ -188,7 +188,7 @@ QModelIndex QUndoModel::parent(const QModelIndex&) const
 
 int QUndoModel::rowCount(const QModelIndex &parent) const
 {
-    if (m_stack == 0)
+    if (m_stack == nullptr)
         return 0;
 
     if (parent.isValid())
@@ -204,7 +204,7 @@ int QUndoModel::columnCount(const QModelIndex&) const
 
 QVariant QUndoModel::data(const QModelIndex &index, int role) const
 {
-    if (m_stack == 0)
+    if (m_stack == nullptr)
         return QVariant();
 
     if (index.column() != 0)
@@ -274,9 +274,9 @@ class QUndoViewPrivate : public QListViewPrivate
 public:
     QUndoViewPrivate() :
 #if QT_CONFIG(undogroup)
-        group(0),
+        group(nullptr),
 #endif
-        model(0) {}
+        model(nullptr) {}
 
 #if QT_CONFIG(undogroup)
     QPointer<QUndoGroup> group;
@@ -370,7 +370,7 @@ void QUndoView::setStack(QUndoStack *stack)
 {
     Q_D(QUndoView);
 #if QT_CONFIG(undogroup)
-    setGroup(0);
+    setGroup(nullptr);
 #endif
     d->model->setStack(stack);
 }
@@ -393,19 +393,19 @@ void QUndoView::setGroup(QUndoGroup *group)
     if (d->group == group)
         return;
 
-    if (d->group != 0) {
+    if (d->group != nullptr) {
         disconnect(d->group, SIGNAL(activeStackChanged(QUndoStack*)),
                 d->model, SLOT(setStack(QUndoStack*)));
     }
 
     d->group = group;
 
-    if (d->group != 0) {
+    if (d->group != nullptr) {
         connect(d->group, SIGNAL(activeStackChanged(QUndoStack*)),
                 d->model, SLOT(setStack(QUndoStack*)));
         d->model->setStack(d->group->activeStack());
     } else {
-        d->model->setStack(0);
+        d->model->setStack(nullptr);
     }
 }
 
diff --git a/src/widgets/widgets/qabstractbutton.cpp b/src/widgets/widgets/qabstractbutton.cpp
index 19528d61d2..022f41738c 100644
--- a/src/widgets/widgets/qabstractbutton.cpp
+++ b/src/widgets/widgets/qabstractbutton.cpp
@@ -177,7 +177,7 @@ QAbstractButtonPrivate::QAbstractButtonPrivate(QSizePolicy::ControlType type)
     checkable(false), checked(false), autoRepeat(false), autoExclusive(false),
     down(false), blockRefresh(false), pressed(false),
 #if QT_CONFIG(buttongroup)
-    group(0),
+    group(nullptr),
 #endif
     autoRepeatDelay(AUTO_REPEAT_DELAY),
     autoRepeatInterval(AUTO_REPEAT_INTERVAL),
@@ -217,14 +217,14 @@ QAbstractButton *QAbstractButtonPrivate::queryCheckedButton() const
     Q_Q(const QAbstractButton);
     QList<QAbstractButton *> buttonList = queryButtonList();
     if (!autoExclusive || buttonList.count() == 1) // no group
-        return 0;
+        return nullptr;
 
     for (int i = 0; i < buttonList.count(); ++i) {
         QAbstractButton *b = buttonList.at(i);
         if (b->d_func()->checked && b != q)
             return b;
     }
-    return checked  ? const_cast<QAbstractButton *>(q) : 0;
+    return checked  ? const_cast<QAbstractButton *>(q) : nullptr;
 }
 
 void QAbstractButtonPrivate::notifyChecked()
@@ -257,7 +257,7 @@ void QAbstractButtonPrivate::moveFocus(int key)
     if (!fb || !buttonList.contains(fb))
         return;
 
-    QAbstractButton *candidate = 0;
+    QAbstractButton *candidate = nullptr;
     int bestScore = -1;
     QRect target = f->rect().translated(f->mapToGlobal(QPoint(0,0)));
     QPoint goal = target.center();
@@ -1272,7 +1272,7 @@ QSize QAbstractButton::iconSize() const
     Q_D(const QAbstractButton);
     if (d->iconSize.isValid())
         return d->iconSize;
-    int e = style()->pixelMetric(QStyle::PM_ButtonIconSize, 0, this);
+    int e = style()->pixelMetric(QStyle::PM_ButtonIconSize, nullptr, this);
     return QSize(e, e);
 }
 
diff --git a/src/widgets/widgets/qabstractscrollarea.cpp b/src/widgets/widgets/qabstractscrollarea.cpp
index d2372a7be9..320b3bf7ef 100644
--- a/src/widgets/widgets/qabstractscrollarea.cpp
+++ b/src/widgets/widgets/qabstractscrollarea.cpp
@@ -161,10 +161,10 @@ QT_BEGIN_NAMESPACE
 */
 
 QAbstractScrollAreaPrivate::QAbstractScrollAreaPrivate()
-    :hbar(0), vbar(0), vbarpolicy(Qt::ScrollBarAsNeeded), hbarpolicy(Qt::ScrollBarAsNeeded),
+    :hbar(nullptr), vbar(nullptr), vbarpolicy(Qt::ScrollBarAsNeeded), hbarpolicy(Qt::ScrollBarAsNeeded),
      shownOnce(false), inResize(false), sizeAdjustPolicy(QAbstractScrollArea::AdjustIgnored),
-     viewport(0), cornerWidget(0), left(0), top(0), right(0), bottom(0),
-     xoffset(0), yoffset(0), viewportFilter(0)
+     viewport(nullptr), cornerWidget(nullptr), left(0), top(0), right(0), bottom(0),
+     xoffset(0), yoffset(0), viewportFilter(nullptr)
 {
 }
 
@@ -329,12 +329,12 @@ void QAbstractScrollAreaPrivate::layoutChildren()
 void QAbstractScrollAreaPrivate::layoutChildren_helper(bool *needHorizontalScrollbar, bool *needVerticalScrollbar)
 {
     Q_Q(QAbstractScrollArea);
-    bool htransient = hbar->style()->styleHint(QStyle::SH_ScrollBar_Transient, 0, hbar);
+    bool htransient = hbar->style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, hbar);
     bool needh = *needHorizontalScrollbar || ((hbarpolicy != Qt::ScrollBarAlwaysOff) && ((hbarpolicy == Qt::ScrollBarAlwaysOn && !htransient)
                             || ((hbarpolicy == Qt::ScrollBarAsNeeded || htransient)
                             && hbar->minimum() < hbar->maximum() && !hbar->sizeHint().isEmpty())));
 
-    bool vtransient = vbar->style()->styleHint(QStyle::SH_ScrollBar_Transient, 0, vbar);
+    bool vtransient = vbar->style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, vbar);
     bool needv = *needVerticalScrollbar || ((vbarpolicy != Qt::ScrollBarAlwaysOff) && ((vbarpolicy == Qt::ScrollBarAlwaysOn && !vtransient)
                             || ((vbarpolicy == Qt::ScrollBarAsNeeded || vtransient)
                             && vbar->minimum() < vbar->maximum() && !vbar->sizeHint().isEmpty())));
@@ -352,7 +352,7 @@ void QAbstractScrollAreaPrivate::layoutChildren_helper(bool *needHorizontalScrol
 
     const QRect widgetRect = q->rect();
 
-    const bool hasCornerWidget = (cornerWidget != 0);
+    const bool hasCornerWidget = (cornerWidget != nullptr);
 
     QPoint cornerOffset((needv && vscrollOverlap == 0) ? vsbExt : 0, (needh && hscrollOverlap == 0) ? hsbExt : 0);
     QRect controlsRect;
@@ -794,7 +794,7 @@ void QAbstractScrollArea::addScrollBarWidget(QWidget *widget, Qt::Alignment alig
 {
     Q_D(QAbstractScrollArea);
 
-    if (widget == 0)
+    if (widget == nullptr)
         return;
 
     const Qt::Orientation scrollBarOrientation
@@ -894,8 +894,8 @@ bool QAbstractScrollArea::eventFilter(QObject *o, QEvent *e)
         if (d->hbarpolicy == Qt::ScrollBarAsNeeded && d->vbarpolicy == Qt::ScrollBarAsNeeded) {
             QScrollBar *sbar = static_cast<QScrollBar*>(o);
             QScrollBar *sibling = sbar == d->hbar ? d->vbar : d->hbar;
-            if (sbar->style()->styleHint(QStyle::SH_ScrollBar_Transient, 0, sbar) &&
-                    sibling->style()->styleHint(QStyle::SH_ScrollBar_Transient, 0, sibling))
+            if (sbar->style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, sbar) &&
+                    sibling->style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, sibling))
                 d->setScrollBarTransient(sibling, e->type() == QEvent::HoverLeave);
         }
     }
@@ -1389,10 +1389,10 @@ bool QAbstractScrollAreaPrivate::canStartScrollingAt( const QPoint &startPos )
 
 void QAbstractScrollAreaPrivate::flashScrollBars()
 {
-    bool htransient = hbar->style()->styleHint(QStyle::SH_ScrollBar_Transient, 0, hbar);
+    bool htransient = hbar->style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, hbar);
     if ((hbarpolicy != Qt::ScrollBarAlwaysOff) && (hbarpolicy == Qt::ScrollBarAsNeeded || htransient))
         hbar->d_func()->flash();
-    bool vtransient = vbar->style()->styleHint(QStyle::SH_ScrollBar_Transient, 0, vbar);
+    bool vtransient = vbar->style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, vbar);
     if ((vbarpolicy != Qt::ScrollBarAlwaysOff) && (vbarpolicy == Qt::ScrollBarAsNeeded || vtransient))
         vbar->d_func()->flash();
 }
diff --git a/src/widgets/widgets/qabstractspinbox.cpp b/src/widgets/widgets/qabstractspinbox.cpp
index b1e1c9bc1b..6a0d2f5019 100644
--- a/src/widgets/widgets/qabstractspinbox.cpp
+++ b/src/widgets/widgets/qabstractspinbox.cpp
@@ -848,9 +848,9 @@ void QAbstractSpinBox::changeEvent(QEvent *event)
 
     switch (event->type()) {
         case QEvent::StyleChange:
-            d->spinClickTimerInterval = style()->styleHint(QStyle::SH_SpinBox_ClickAutoRepeatRate, 0, this);
+            d->spinClickTimerInterval = style()->styleHint(QStyle::SH_SpinBox_ClickAutoRepeatRate, nullptr, this);
             d->spinClickThresholdTimerInterval =
-                style()->styleHint(QStyle::SH_SpinBox_ClickAutoRepeatThreshold, 0, this);
+                style()->styleHint(QStyle::SH_SpinBox_ClickAutoRepeatThreshold, nullptr, this);
             if (d->edit)
                 d->edit->setFrame(!style()->styleHint(QStyle::SH_SpinBox_ButtonsInsideFrame, nullptr, this));
             d->stepModifier = static_cast<Qt::KeyboardModifier>(style()->styleHint(QStyle::SH_SpinBox_StepModifier, nullptr, this));
@@ -1043,7 +1043,7 @@ void QAbstractSpinBox::keyPressEvent(QKeyEvent *event)
             steps *= 10;
         if (!up)
             steps *= -1;
-        if (style()->styleHint(QStyle::SH_SpinBox_AnimateButton, 0, this)) {
+        if (style()->styleHint(QStyle::SH_SpinBox_AnimateButton, nullptr, this)) {
             d->buttonState = (Keyboard | (up ? Up : Down));
         }
         if (d->spinClickTimerId == -1)
@@ -1421,14 +1421,14 @@ void QAbstractSpinBox::mouseReleaseEvent(QMouseEvent *event)
 */
 
 QAbstractSpinBoxPrivate::QAbstractSpinBoxPrivate()
-    : edit(0), type(QVariant::Invalid), spinClickTimerId(-1),
+    : edit(nullptr), type(QVariant::Invalid), spinClickTimerId(-1),
       spinClickTimerInterval(100), spinClickThresholdTimerId(-1), spinClickThresholdTimerInterval(-1),
       effectiveSpinRepeatRate(1), buttonState(None), cachedText(QLatin1String("\x01")),
       cachedState(QValidator::Invalid), pendingEmit(false), readOnly(false), wrapping(false),
       ignoreCursorPositionChanged(false), frame(true), accelerate(false), keyboardTracking(true),
       cleared(false), ignoreUpdateEdit(false), correctionMode(QAbstractSpinBox::CorrectToPreviousValue),
       stepModifier(Qt::ControlModifier), acceleration(0), hoverControl(QStyle::SC_None),
-      buttonSymbols(QAbstractSpinBox::UpDownArrows), validator(0), showGroupSeparator(0),
+      buttonSymbols(QAbstractSpinBox::UpDownArrows), validator(nullptr), showGroupSeparator(0),
       wheelDeltaRemainder(0)
 {
 }
diff --git a/src/widgets/widgets/qbuttongroup.cpp b/src/widgets/widgets/qbuttongroup.cpp
index 669faa92c7..c3fd37d8e9 100644
--- a/src/widgets/widgets/qbuttongroup.cpp
+++ b/src/widgets/widgets/qbuttongroup.cpp
@@ -47,7 +47,7 @@ QT_BEGIN_NAMESPACE
 void QButtonGroupPrivate::detectCheckedButton()
 {
     QAbstractButton *previous = checkedButton;
-    checkedButton = 0;
+    checkedButton = nullptr;
     if (exclusive)
         return;
     for (int i = 0; i < buttonList.count(); i++) {
@@ -119,7 +119,7 @@ QButtonGroup::~QButtonGroup()
 {
     Q_D(QButtonGroup);
     for (int i = 0; i < d->buttonList.count(); ++i)
-        d->buttonList.at(i)->d_func()->group = 0;
+        d->buttonList.at(i)->d_func()->group = nullptr;
 }
 
 /*!
@@ -273,7 +273,7 @@ void QButtonGroup::removeButton(QAbstractButton *button)
         d->detectCheckedButton();
     }
     if (button->d_func()->group == this) {
-        button->d_func()->group = 0;
+        button->d_func()->group = nullptr;
         d->buttonList.removeAll(button);
         d->mapping.remove(button);
     }
diff --git a/src/widgets/widgets/qcalendarwidget.cpp b/src/widgets/widgets/qcalendarwidget.cpp
index 749ae96df2..fe1133c6c7 100644
--- a/src/widgets/widgets/qcalendarwidget.cpp
+++ b/src/widgets/widgets/qcalendarwidget.cpp
@@ -559,7 +559,7 @@ void QCalendarDateValidator::setFormat(const QString &format)
                 separator += nextChar;
                 quoting = false;
             } else {
-                QCalendarDateSectionValidator *validator = 0;
+                QCalendarDateSectionValidator *validator = nullptr;
                 if (nextChar == QLatin1Char('d')) {
                     offset = qMin(4, countRepeat(format, pos));
                     validator = &m_dayValidator;
@@ -640,9 +640,9 @@ class QCalendarTextNavigator: public QObject
 {
     Q_OBJECT
 public:
-    QCalendarTextNavigator(QObject *parent = 0)
-        : QObject(parent), m_dateText(0), m_dateFrame(0), m_dateValidator(0),
-          m_widget(0), m_editDelay(1500), m_date(QDate::currentDate()) {}
+    QCalendarTextNavigator(QObject *parent = nullptr)
+        : QObject(parent), m_dateText(nullptr), m_dateFrame(nullptr), m_dateValidator(nullptr),
+          m_widget(nullptr), m_editDelay(1500), m_date(QDate::currentDate()) {}
 
     QWidget *widget() const;
     void setWidget(QWidget *widget);
@@ -752,9 +752,9 @@ void QCalendarTextNavigator::removeDateLabel()
     m_dateFrame->hide();
     m_dateFrame->deleteLater();
     delete m_dateValidator;
-    m_dateFrame = 0;
-    m_dateText = 0;
-    m_dateValidator = 0;
+    m_dateFrame = nullptr;
+    m_dateText = nullptr;
+    m_dateValidator = nullptr;
 }
 
 bool QCalendarTextNavigator::eventFilter(QObject *o, QEvent *e)
@@ -858,7 +858,7 @@ class QCalendarModel : public QAbstractTableModel
 {
     Q_OBJECT
 public:
-    QCalendarModel(QObject *parent = 0);
+    QCalendarModel(QObject *parent = nullptr);
 
     int rowCount(const QModelIndex &) const override
         { return RowCount + m_firstRow; }
@@ -951,7 +951,7 @@ class QCalendarView : public QTableView
 {
     Q_OBJECT
 public:
-    QCalendarView(QWidget *parent = 0);
+    QCalendarView(QWidget *parent = nullptr);
 
     void internalUpdate() { updateGeometries(); }
     void setReadOnly(bool enable);
@@ -1599,7 +1599,7 @@ class QCalendarDelegate : public QItemDelegate
 {
     Q_OBJECT
 public:
-    QCalendarDelegate(QCalendarWidgetPrivate *w, QObject *parent = 0)
+    QCalendarDelegate(QCalendarWidgetPrivate *w, QObject *parent = nullptr)
         : QItemDelegate(parent), calendarWidgetPrivate(w)
             { }
     virtual void paint(QPainter *painter, const QStyleOptionViewItem &option,
@@ -1734,11 +1734,11 @@ void QCalendarDelegate::paintCell(QPainter *painter, const QRect &rect, QDate da
 QCalendarWidgetPrivate::QCalendarWidgetPrivate()
     : QWidgetPrivate()
 {
-    m_model = 0;
-    m_view = 0;
-    m_delegate = 0;
-    m_selection = 0;
-    m_navigator = 0;
+    m_model = nullptr;
+    m_view = nullptr;
+    m_delegate = nullptr;
+    m_selection = nullptr;
+    m_navigator = nullptr;
     m_dateEditEnabled = false;
     navBarVisible = true;
     oldFocusPolicy = Qt::StrongFocus;
@@ -1748,7 +1748,7 @@ void QCalendarWidgetPrivate::setNavigatorEnabled(bool enable)
 {
     Q_Q(QCalendarWidget);
 
-    bool navigatorEnabled = (m_navigator->widget() != 0);
+    bool navigatorEnabled = (m_navigator->widget() != nullptr);
     if (enable == navigatorEnabled)
         return;
 
@@ -1760,7 +1760,7 @@ void QCalendarWidgetPrivate::setNavigatorEnabled(bool enable)
                 q, SLOT(_q_editingFinished()));
         m_view->installEventFilter(m_navigator);
     } else {
-        m_navigator->setWidget(0);
+        m_navigator->setWidget(nullptr);
         q->disconnect(m_navigator, SIGNAL(dateChanged(QDate)),
                 q, SLOT(_q_slotChangeDate(QDate)));
         q->disconnect(m_navigator, SIGNAL(editingFinished()),
@@ -1847,8 +1847,8 @@ void QCalendarWidgetPrivate::createNavigationBar(QWidget *widget)
 void QCalendarWidgetPrivate::updateButtonIcons()
 {
     Q_Q(QCalendarWidget);
-    prevMonth->setIcon(q->style()->standardIcon(q->isRightToLeft() ? QStyle::SP_ArrowRight : QStyle::SP_ArrowLeft, 0, q));
-    nextMonth->setIcon(q->style()->standardIcon(q->isRightToLeft() ? QStyle::SP_ArrowLeft : QStyle::SP_ArrowRight, 0, q));
+    prevMonth->setIcon(q->style()->standardIcon(q->isRightToLeft() ? QStyle::SP_ArrowRight : QStyle::SP_ArrowLeft, nullptr, q));
+    nextMonth->setIcon(q->style()->standardIcon(q->isRightToLeft() ? QStyle::SP_ArrowLeft : QStyle::SP_ArrowRight, nullptr, q));
 }
 
 void QCalendarWidgetPrivate::updateMonthMenu()
diff --git a/src/widgets/widgets/qdatetimeedit.cpp b/src/widgets/widgets/qdatetimeedit.cpp
index 3be163ff75..8c8aaf8ae3 100644
--- a/src/widgets/widgets/qdatetimeedit.cpp
+++ b/src/widgets/widgets/qdatetimeedit.cpp
@@ -764,7 +764,7 @@ QCalendarWidget *QDateTimeEdit::calendarWidget() const
 {
     Q_D(const QDateTimeEdit);
     if (!d->calendarPopup || !(d->sections & QDateTimeParser::DateSectionMask))
-        return 0;
+        return nullptr;
     if (!d->monthCalendar) {
         const_cast<QDateTimeEditPrivate*>(d)->initCalendarPopup();
     }
@@ -1221,7 +1221,7 @@ void QDateTimeEdit::focusInEvent(QFocusEvent *event)
 {
     Q_D(QDateTimeEdit);
     QAbstractSpinBox::focusInEvent(event);
-    QString *frm = 0;
+    QString *frm = nullptr;
     const int oldPos = d->edit->cursorPosition();
     if (!d->formatExplicitlySet) {
         if (d->displayFormat == d->defaultTimeFormat) {
@@ -1668,7 +1668,7 @@ QDateTimeEditPrivate::QDateTimeEditPrivate()
     minimum = QDATETIMEEDIT_COMPAT_DATE_MIN.startOfDay();
     maximum = QDATETIMEEDIT_DATE_MAX.endOfDay();
     arrowState = QStyle::State_None;
-    monthCalendar = 0;
+    monthCalendar = nullptr;
     readLocaleSettings();
 
 #ifdef QT_KEYPAD_NAVIGATION
diff --git a/src/widgets/widgets/qdialogbuttonbox.cpp b/src/widgets/widgets/qdialogbuttonbox.cpp
index 9096ee82f6..9867cb5540 100644
--- a/src/widgets/widgets/qdialogbuttonbox.cpp
+++ b/src/widgets/widgets/qdialogbuttonbox.cpp
@@ -178,15 +178,15 @@ public:
 };
 
 QDialogButtonBoxPrivate::QDialogButtonBoxPrivate(Qt::Orientation orient)
-    : orientation(orient), buttonLayout(0), internalRemove(false), center(false)
+    : orientation(orient), buttonLayout(nullptr), internalRemove(false), center(false)
 {
 }
 
 void QDialogButtonBoxPrivate::initLayout()
 {
     Q_Q(QDialogButtonBox);
-    layoutPolicy = QDialogButtonBox::ButtonLayout(q->style()->styleHint(QStyle::SH_DialogButtonLayout, 0, q));
-    bool createNewLayout = buttonLayout == 0
+    layoutPolicy = QDialogButtonBox::ButtonLayout(q->style()->styleHint(QStyle::SH_DialogButtonLayout, nullptr, q));
+    bool createNewLayout = buttonLayout == nullptr
         || (orientation == Qt::Horizontal && qobject_cast<QVBoxLayout *>(buttonLayout) != 0)
         || (orientation == Qt::Vertical && qobject_cast<QHBoxLayout *>(buttonLayout) != 0);
     if (createNewLayout) {
@@ -329,8 +329,8 @@ void QDialogButtonBoxPrivate::layoutButtons()
         ++currentLayout;
     }
 
-    QWidget *lastWidget = 0;
-    q->setFocusProxy(0);
+    QWidget *lastWidget = nullptr;
+    q->setFocusProxy(nullptr);
     for (int i = 0; i < buttonLayout->count(); ++i) {
         QLayoutItem *item = buttonLayout->itemAt(i);
         if (QWidget *widget = item->widget()) {
@@ -408,13 +408,13 @@ QPushButton *QDialogButtonBoxPrivate::createButton(QDialogButtonBox::StandardBut
         icon = QStyle::SP_RestoreDefaultsButton;
         break;
     case QDialogButtonBox::NoButton:
-        return 0;
+        return nullptr;
         ;
     }
     QPushButton *button = new QPushButton(QGuiApplicationPrivate::platformTheme()->standardButtonText(sbutton), q);
     QStyle *style = q->style();
-    if (style->styleHint(QStyle::SH_DialogButtonBox_ButtonsHaveIcons, 0, q) && icon != 0)
-        button->setIcon(style->standardIcon(QStyle::StandardPixmap(icon), 0, q));
+    if (style->styleHint(QStyle::SH_DialogButtonBox_ButtonsHaveIcons, nullptr, q) && icon != 0)
+        button->setIcon(style->standardIcon(QStyle::StandardPixmap(icon), nullptr, q));
     if (style != QApplication::style()) // Propagate style
         button->setStyle(style);
     standardButtonHash.insert(button, sbutton);
@@ -743,7 +743,7 @@ void QDialogButtonBox::removeButton(QAbstractButton *button)
         }
     }
     if (!d->internalRemove)
-        button->setParent(0);
+        button->setParent(nullptr);
 }
 
 /*!
@@ -781,7 +781,7 @@ QPushButton *QDialogButtonBox::addButton(const QString &text, ButtonRole role)
     Q_D(QDialogButtonBox);
     if (Q_UNLIKELY(role <= InvalidRole || role >= NRoles)) {
         qWarning("QDialogButtonBox::addButton: Invalid ButtonRole, button not added");
-        return 0;
+        return nullptr;
     }
     QPushButton *button = new QPushButton(text, this);
     d->addButton(button, role);
@@ -963,7 +963,7 @@ bool QDialogButtonBox::event(QEvent *event)
         QList<QAbstractButton *> acceptRoleList = d->buttonLists[AcceptRole];
         QPushButton *firstAcceptButton = acceptRoleList.isEmpty() ? 0 : qobject_cast<QPushButton *>(acceptRoleList.at(0));
         bool hasDefault = false;
-        QWidget *dialog = 0;
+        QWidget *dialog = nullptr;
         QWidget *p = this;
         while (p && !p->isWindow()) {
             p = p->parentWidget();
diff --git a/src/widgets/widgets/qdockarealayout.cpp b/src/widgets/widgets/qdockarealayout.cpp
index 5900326087..87f4519dd6 100644
--- a/src/widgets/widgets/qdockarealayout.cpp
+++ b/src/widgets/widgets/qdockarealayout.cpp
@@ -85,27 +85,27 @@ QPlaceHolderItem::QPlaceHolderItem(QWidget *w)
 */
 
 QDockAreaLayoutItem::QDockAreaLayoutItem(QLayoutItem *_widgetItem)
-    : widgetItem(_widgetItem), subinfo(0), placeHolderItem(0), pos(0), size(-1), flags(NoFlags)
+    : widgetItem(_widgetItem), subinfo(nullptr), placeHolderItem(nullptr), pos(0), size(-1), flags(NoFlags)
 {
 }
 
 QDockAreaLayoutItem::QDockAreaLayoutItem(QDockAreaLayoutInfo *_subinfo)
-    : widgetItem(0), subinfo(_subinfo), placeHolderItem(0), pos(0), size(-1), flags(NoFlags)
+    : widgetItem(nullptr), subinfo(_subinfo), placeHolderItem(nullptr), pos(0), size(-1), flags(NoFlags)
 {
 }
 
 QDockAreaLayoutItem::QDockAreaLayoutItem(QPlaceHolderItem *_placeHolderItem)
-    : widgetItem(0), subinfo(0), placeHolderItem(_placeHolderItem), pos(0), size(-1), flags(NoFlags)
+    : widgetItem(nullptr), subinfo(nullptr), placeHolderItem(_placeHolderItem), pos(0), size(-1), flags(NoFlags)
 {
 }
 
 QDockAreaLayoutItem::QDockAreaLayoutItem(const QDockAreaLayoutItem &other)
-    : widgetItem(other.widgetItem), subinfo(0), placeHolderItem(0), pos(other.pos),
+    : widgetItem(other.widgetItem), subinfo(nullptr), placeHolderItem(nullptr), pos(other.pos),
         size(other.size), flags(other.flags)
 {
-    if (other.subinfo != 0)
+    if (other.subinfo != nullptr)
         subinfo = new QDockAreaLayoutInfo(*other.subinfo);
-    else if (other.placeHolderItem != 0)
+    else if (other.placeHolderItem != nullptr)
         placeHolderItem = new QPlaceHolderItem(*other.placeHolderItem);
 }
 
@@ -117,16 +117,16 @@ QDockAreaLayoutItem::~QDockAreaLayoutItem()
 
 bool QDockAreaLayoutItem::skip() const
 {
-    if (placeHolderItem != 0)
+    if (placeHolderItem != nullptr)
         return true;
 
     if (flags & GapItem)
         return false;
 
-    if (widgetItem != 0)
+    if (widgetItem != nullptr)
         return widgetItem->isEmpty();
 
-    if (subinfo != 0) {
+    if (subinfo != nullptr) {
         for (int i = 0; i < subinfo->item_list.count(); ++i) {
             if (!subinfo->item_list.at(i).skip())
                 return false;
@@ -140,7 +140,7 @@ QSize QDockAreaLayoutItem::minimumSize() const
 {
     if (widgetItem)
         return widgetItem->minimumSize().grownBy(widgetItem->widget()->contentsMargins());
-    if (subinfo != 0)
+    if (subinfo != nullptr)
         return subinfo->minimumSize();
     return QSize(0, 0);
 }
@@ -149,7 +149,7 @@ QSize QDockAreaLayoutItem::maximumSize() const
 {
     if (widgetItem)
         return widgetItem->maximumSize().grownBy(widgetItem->widget()->contentsMargins());
-    if (subinfo != 0)
+    if (subinfo != nullptr)
         return subinfo->maximumSize();
     return QSize(QWIDGETSIZE_MAX, QWIDGETSIZE_MAX);
 }
@@ -161,22 +161,22 @@ bool QDockAreaLayoutItem::hasFixedSize(Qt::Orientation o) const
 
 bool QDockAreaLayoutItem::expansive(Qt::Orientation o) const
 {
-    if ((flags & GapItem) || placeHolderItem != 0)
+    if ((flags & GapItem) || placeHolderItem != nullptr)
         return false;
-    if (widgetItem != 0)
+    if (widgetItem != nullptr)
         return ((widgetItem->expandingDirections() & o) == o);
-    if (subinfo != 0)
+    if (subinfo != nullptr)
         return subinfo->expansive(o);
     return false;
 }
 
 QSize QDockAreaLayoutItem::sizeHint() const
 {
-    if (placeHolderItem != 0)
+    if (placeHolderItem != nullptr)
         return QSize(0, 0);
     if (widgetItem)
         return widgetItem->sizeHint().grownBy(widgetItem->widget()->contentsMargins());
-    if (subinfo != 0)
+    if (subinfo != nullptr)
         return subinfo->sizeHint();
     return QSize(-1, -1);
 }
@@ -185,14 +185,14 @@ QDockAreaLayoutItem
     &QDockAreaLayoutItem::operator = (const QDockAreaLayoutItem &other)
 {
     widgetItem = other.widgetItem;
-    if (other.subinfo == 0)
-        subinfo = 0;
+    if (other.subinfo == nullptr)
+        subinfo = nullptr;
     else
         subinfo = new QDockAreaLayoutInfo(*other.subinfo);
 
     delete placeHolderItem;
-    if (other.placeHolderItem == 0)
-        placeHolderItem = 0;
+    if (other.placeHolderItem == nullptr)
+        placeHolderItem = nullptr;
     else
         placeHolderItem = new QPlaceHolderItem(*other.placeHolderItem);
 
@@ -210,7 +210,7 @@ QDockAreaLayoutItem
 #if QT_CONFIG(tabbar)
 static quintptr tabId(const QDockAreaLayoutItem &item)
 {
-    if (item.widgetItem == 0)
+    if (item.widgetItem == nullptr)
         return 0;
     return reinterpret_cast<quintptr>(item.widgetItem->widget());
 }
@@ -219,9 +219,9 @@ static quintptr tabId(const QDockAreaLayoutItem &item)
 static const int zero = 0;
 
 QDockAreaLayoutInfo::QDockAreaLayoutInfo()
-    : sep(&zero), dockPos(QInternal::LeftDock), o(Qt::Horizontal), mainWindow(0)
+    : sep(&zero), dockPos(QInternal::LeftDock), o(Qt::Horizontal), mainWindow(nullptr)
 #if QT_CONFIG(tabbar)
-    , tabbed(false), tabBar(0), tabBarShape(QTabBar::RoundedSouth)
+    , tabbed(false), tabBar(nullptr), tabBarShape(QTabBar::RoundedSouth)
 #endif
 {
 }
@@ -231,7 +231,7 @@ QDockAreaLayoutInfo::QDockAreaLayoutInfo(const int *_sep, QInternal::DockPositio
                                             QMainWindow *window)
     : sep(_sep), dockPos(_dockPos), o(_o), mainWindow(window)
 #if QT_CONFIG(tabbar)
-    , tabbed(false), tabBar(0), tabBarShape(static_cast<QTabBar::Shape>(tbshape))
+    , tabbed(false), tabBar(nullptr), tabBarShape(static_cast<QTabBar::Shape>(tbshape))
 #endif
 {
 #if !QT_CONFIG(tabbar)
@@ -250,7 +250,7 @@ void QDockAreaLayoutInfo::clear()
     rect = QRect();
 #if QT_CONFIG(tabbar)
     tabbed = false;
-    tabBar = 0;
+    tabBar = nullptr;
 #endif
 }
 
@@ -403,7 +403,7 @@ QSize QDockAreaLayoutInfo::sizeHint() const
     int a = 0, b = 0;
     int min_perp = 0;
     int max_perp = QWIDGETSIZE_MAX;
-    const QDockAreaLayoutItem *previous = 0;
+    const QDockAreaLayoutItem *previous = nullptr;
     for (int i = 0; i < item_list.size(); ++i) {
         const QDockAreaLayoutItem &item = item_list.at(i);
         if (item.skip())
@@ -552,7 +552,7 @@ void QDockAreaLayoutInfo::fitItems()
     int max_size = realMaxSize(*this);
     int last_index = -1;
 
-    const QDockAreaLayoutItem *previous = 0;
+    const QDockAreaLayoutItem *previous = nullptr;
     for (int i = 0; i < item_list.size(); ++i) {
         QDockAreaLayoutItem &item = item_list[i];
         if (item.skip())
@@ -633,7 +633,7 @@ void QDockAreaLayoutInfo::fitItems()
         item.size = ls.size;
         item.pos = ls.pos;
 
-        if (item.subinfo != 0) {
+        if (item.subinfo != nullptr) {
             item.subinfo->rect = itemRect(i);
             item.subinfo->fitItems();
         }
@@ -771,7 +771,7 @@ QList<int> QDockAreaLayoutInfo::gapIndex(const QPoint& _pos,
             if (item.pos + item.size < pos)
                 continue;
 
-            if (item.subinfo != 0
+            if (item.subinfo != nullptr
 #if QT_CONFIG(tabbar)
                 && !item.subinfo->tabbed
 #endif
@@ -967,7 +967,7 @@ int QDockAreaLayoutInfo::separatorMove(int index, int delta)
         const int separatorSpace = item.hasFixedSize(o) ? 0 : *sep;
         item.size = ls.size - separatorSpace;
         item.pos = ls.pos;
-        if (item.subinfo != 0) {
+        if (item.subinfo != nullptr) {
             item.subinfo->rect = itemRect(i);
             item.subinfo->fitItems();
         }
@@ -979,7 +979,7 @@ int QDockAreaLayoutInfo::separatorMove(int index, int delta)
 void QDockAreaLayoutInfo::unnest(int index)
 {
     QDockAreaLayoutItem &item = item_list[index];
-    if (item.subinfo == 0)
+    if (item.subinfo == nullptr)
         return;
     if (item.subinfo->item_list.count() > 1)
         return;
@@ -988,14 +988,14 @@ void QDockAreaLayoutInfo::unnest(int index)
         item_list.removeAt(index);
     } else if (item.subinfo->item_list.count() == 1) {
         QDockAreaLayoutItem &child = item.subinfo->item_list.first();
-        if (child.widgetItem != 0) {
+        if (child.widgetItem != nullptr) {
             item.widgetItem = child.widgetItem;
             delete item.subinfo;
-            item.subinfo = 0;
-        } else if (child.subinfo != 0) {
+            item.subinfo = nullptr;
+        } else if (child.subinfo != nullptr) {
             QDockAreaLayoutInfo *tmp = item.subinfo;
             item.subinfo = child.subinfo;
-            child.subinfo = 0;
+            child.subinfo = nullptr;
             tmp->item_list.clear();
             delete tmp;
         }
@@ -1009,7 +1009,7 @@ void QDockAreaLayoutInfo::remove(const QList<int> &path)
     if (path.count() > 1) {
         const int index = path.first();
         QDockAreaLayoutItem &item = item_list[index];
-        Q_ASSERT(item.subinfo != 0);
+        Q_ASSERT(item.subinfo != nullptr);
         item.subinfo->remove(path.mid(1));
         unnest(index);
     } else {
@@ -1028,13 +1028,13 @@ QLayoutItem *QDockAreaLayoutInfo::plug(const QList<int> &path)
 
     if (path.count() > 1) {
         QDockAreaLayoutItem &item = item_list[index];
-        Q_ASSERT(item.subinfo != 0);
+        Q_ASSERT(item.subinfo != nullptr);
         return item.subinfo->plug(path.mid(1));
     }
 
     QDockAreaLayoutItem &item = item_list[index];
 
-    Q_ASSERT(item.widgetItem != 0);
+    Q_ASSERT(item.widgetItem != nullptr);
     Q_ASSERT(item.flags & QDockAreaLayoutItem::GapItem);
     item.flags &= ~QDockAreaLayoutItem::GapItem;
     return item.widgetItem;
@@ -1047,7 +1047,7 @@ QLayoutItem *QDockAreaLayoutInfo::unplug(const QList<int> &path)
     const int index = path.first();
     if (path.count() > 1) {
         QDockAreaLayoutItem &item = item_list[index];
-        Q_ASSERT(item.subinfo != 0);
+        Q_ASSERT(item.subinfo != nullptr);
         return item.subinfo->unplug(path.mid(1));
     }
 
@@ -1078,7 +1078,7 @@ QLayoutItem *QDockAreaLayoutInfo::unplug(const QList<int> &path)
 
 quintptr QDockAreaLayoutInfo::currentTabId() const
 {
-    if (!tabbed || tabBar == 0)
+    if (!tabbed || tabBar == nullptr)
         return 0;
 
     int index = tabBar->currentIndex();
@@ -1095,7 +1095,7 @@ void QDockAreaLayoutInfo::setCurrentTab(QWidget *widget)
 
 void QDockAreaLayoutInfo::setCurrentTabId(quintptr id)
 {
-    if (!tabbed || tabBar == 0)
+    if (!tabbed || tabBar == nullptr)
         return;
 
     for (int i = 0; i < tabBar->count(); ++i) {
@@ -1114,7 +1114,7 @@ static QRect dockedGeometry(QWidget *widget)
 
     QDockWidgetLayout *layout
         = qobject_cast<QDockWidgetLayout*>(widget->layout());
-    if(layout != 0 && layout->nativeWindowDeco())
+    if (layout && layout->nativeWindowDeco())
         titleHeight = layout->titleHeight();
 
     QRect result = widget->geometry();
@@ -1138,7 +1138,7 @@ bool QDockAreaLayoutInfo::insertGap(const QList<int> &path, QLayoutItem *dockWid
     if (path.count() > 1) {
         QDockAreaLayoutItem &item = item_list[index];
 
-        if (item.subinfo == 0
+        if (item.subinfo == nullptr
 #if QT_CONFIG(tabbar)
             || (item.subinfo->tabbed && !insert_tabbed)
 #endif
@@ -1149,7 +1149,7 @@ bool QDockAreaLayoutInfo::insertGap(const QList<int> &path, QLayoutItem *dockWid
             QDockAreaLayoutInfo *subinfo = item.subinfo;
             QLayoutItem *widgetItem = item.widgetItem;
             QPlaceHolderItem *placeHolderItem = item.placeHolderItem;
-            QRect r = subinfo == 0 ? widgetItem ? dockedGeometry(widgetItem->widget()) : placeHolderItem->topLevelRect : subinfo->rect;
+            QRect r = subinfo == nullptr ? widgetItem ? dockedGeometry(widgetItem->widget()) : placeHolderItem->topLevelRect : subinfo->rect;
 
             Qt::Orientation opposite = o == Qt::Horizontal ? Qt::Vertical : Qt::Horizontal;
 #if !QT_CONFIG(tabbar)
@@ -1160,11 +1160,11 @@ bool QDockAreaLayoutInfo::insertGap(const QList<int> &path, QLayoutItem *dockWid
 
             //item become a new top-level
             item.subinfo = new_info;
-            item.widgetItem = 0;
-            item.placeHolderItem = 0;
+            item.widgetItem = nullptr;
+            item.placeHolderItem = nullptr;
 
             QDockAreaLayoutItem new_item
-                = widgetItem == 0
+                = widgetItem == nullptr
                     ? QDockAreaLayoutItem(subinfo)
                     : widgetItem ? QDockAreaLayoutItem(widgetItem) : QDockAreaLayoutItem(placeHolderItem);
             new_item.size = pick(opposite, r.size());
@@ -1265,16 +1265,16 @@ QDockAreaLayoutInfo *QDockAreaLayoutInfo::info(QWidget *widget)
             return this;
 #endif
 
-        if (item.widgetItem != 0 && item.widgetItem->widget() == widget)
+        if (item.widgetItem != nullptr && item.widgetItem->widget() == widget)
             return this;
 
-        if (item.subinfo != 0) {
+        if (item.subinfo != nullptr) {
             if (QDockAreaLayoutInfo *result = item.subinfo->info(widget))
                 return result;
         }
     }
 
-    return 0;
+    return nullptr;
 }
 
 QDockAreaLayoutInfo *QDockAreaLayoutInfo::info(const QList<int> &path)
@@ -1284,7 +1284,7 @@ QDockAreaLayoutInfo *QDockAreaLayoutInfo::info(const QList<int> &path)
         index = -index - 1;
     if (index >= item_list.count())
         return this;
-    if (path.count() == 1 || item_list[index].subinfo == 0)
+    if (path.count() == 1 || item_list[index].subinfo == nullptr)
         return this;
     return item_list[index].subinfo->info(path.mid(1));
 }
@@ -1341,7 +1341,7 @@ QRect QDockAreaLayoutInfo::itemRect(const QList<int> &path) const
     const int index = path.first();
     if (path.count() > 1) {
         const QDockAreaLayoutItem &item = item_list.at(index);
-        Q_ASSERT(item.subinfo != 0);
+        Q_ASSERT(item.subinfo != nullptr);
         return item.subinfo->itemRect(path.mid(1));
     }
 
@@ -1374,7 +1374,7 @@ QRect QDockAreaLayoutInfo::separatorRect(const QList<int> &path) const
     const int index = path.first();
     if (path.count() > 1) {
         const QDockAreaLayoutItem &item = item_list.at(index);
-        Q_ASSERT(item.subinfo != 0);
+        Q_ASSERT(item.subinfo != nullptr);
         return item.subinfo->separatorRect(path.mid(1));
     }
     return separatorRect(index);
@@ -1395,7 +1395,7 @@ QList<int> QDockAreaLayoutInfo::findSeparator(const QPoint &_pos) const
             continue;
 
         if (item.pos + item.size > pos) {
-            if (item.subinfo != 0) {
+            if (item.subinfo != nullptr) {
                 QList<int> result = item.subinfo->findSeparator(_pos);
                 if (!result.isEmpty()) {
                     result.prepend(i);
@@ -1428,7 +1428,7 @@ QList<int> QDockAreaLayoutInfo::indexOfPlaceHolder(const QString &objectName) co
     for (int i = 0; i < item_list.size(); ++i) {
         const QDockAreaLayoutItem &item = item_list.at(i);
 
-        if (item.subinfo != 0) {
+        if (item.subinfo != nullptr) {
             QList<int> result = item.subinfo->indexOfPlaceHolder(objectName);
             if (!result.isEmpty()) {
                 result.prepend(i);
@@ -1437,7 +1437,7 @@ QList<int> QDockAreaLayoutInfo::indexOfPlaceHolder(const QString &objectName) co
             continue;
         }
 
-        if (item.placeHolderItem != 0 && item.placeHolderItem->objectName == objectName) {
+        if (item.placeHolderItem != nullptr && item.placeHolderItem->objectName == objectName) {
             QList<int> result;
             result << i;
             return result;
@@ -1452,10 +1452,10 @@ QList<int> QDockAreaLayoutInfo::indexOf(QWidget *widget) const
     for (int i = 0; i < item_list.size(); ++i) {
         const QDockAreaLayoutItem &item = item_list.at(i);
 
-        if (item.placeHolderItem != 0)
+        if (item.placeHolderItem != nullptr)
             continue;
 
-        if (item.subinfo != 0) {
+        if (item.subinfo != nullptr) {
             QList<int> result = item.subinfo->indexOf(widget);
             if (!result.isEmpty()) {
                 result.prepend(i);
@@ -1477,7 +1477,7 @@ QList<int> QDockAreaLayoutInfo::indexOf(QWidget *widget) const
 QMainWindowLayout *QDockAreaLayoutInfo::mainWindowLayout() const
 {
     QMainWindowLayout *result = qt_mainwindow_layout(mainWindow);
-    Q_ASSERT(result != 0);
+    Q_ASSERT(result != nullptr);
     return result;
 }
 
@@ -1536,7 +1536,7 @@ QDockWidget *QDockAreaLayoutInfo::apply(bool animate)
         if (item.flags & QDockAreaLayoutItem::GapItem)
             continue;
 
-        if (item.subinfo != 0) {
+        if (item.subinfo != nullptr) {
             item.subinfo->apply(animate);
             continue;
         }
@@ -1681,7 +1681,7 @@ void QDockAreaLayoutInfo::tab(int index, QLayoutItem *dockWidgetItem)
             = new QDockAreaLayoutInfo(sep, dockPos, o, tabBarShape, mainWindow);
         item_list[index].subinfo = new_info;
         new_info->item_list.append(QDockAreaLayoutItem(item_list.at(index).widgetItem));
-        item_list[index].widgetItem = 0;
+        item_list[index].widgetItem = nullptr;
         new_info->item_list.append(QDockAreaLayoutItem(dockWidgetItem));
         new_info->tabbed = true;
         new_info->updateTabBar();
@@ -1703,7 +1703,7 @@ void QDockAreaLayoutInfo::split(int index, Qt::Orientation orientation,
             = new QDockAreaLayoutInfo(sep, dockPos, orientation, tabBarShape, mainWindow);
         item_list[index].subinfo = new_info;
         new_info->item_list.append(QDockAreaLayoutItem(item_list.at(index).widgetItem));
-        item_list[index].widgetItem = 0;
+        item_list[index].widgetItem = nullptr;
         new_info->item_list.append(QDockAreaLayoutItem(dockWidgetItem));
     }
 }
@@ -1714,7 +1714,7 @@ QDockAreaLayoutItem &QDockAreaLayoutInfo::item(const QList<int> &path)
     const int index = path.first();
     if (path.count() > 1) {
         const QDockAreaLayoutItem &item = item_list[index];
-        Q_ASSERT(item.subinfo != 0);
+        Q_ASSERT(item.subinfo != nullptr);
         return item.subinfo->item(path.mid(1));
     }
     return item_list[index];
@@ -1724,7 +1724,7 @@ QLayoutItem *QDockAreaLayoutInfo::itemAt(int *x, int index) const
 {
     for (int i = 0; i < item_list.count(); ++i) {
         const QDockAreaLayoutItem &item = item_list.at(i);
-        if (item.placeHolderItem != 0)
+        if (item.placeHolderItem != nullptr)
             continue;
         if (item.subinfo) {
             if (QLayoutItem *ret = item.subinfo->itemAt(x, index))
@@ -1734,14 +1734,14 @@ QLayoutItem *QDockAreaLayoutInfo::itemAt(int *x, int index) const
                 return item.widgetItem;
         }
     }
-    return 0;
+    return nullptr;
 }
 
 QLayoutItem *QDockAreaLayoutInfo::takeAt(int *x, int index)
 {
     for (int i = 0; i < item_list.count(); ++i) {
         QDockAreaLayoutItem &item = item_list[i];
-        if (item.placeHolderItem != 0)
+        if (item.placeHolderItem != nullptr)
             continue;
         else if (item.subinfo) {
             if (QLayoutItem *ret = item.subinfo->takeAt(x, index)) {
@@ -1752,14 +1752,14 @@ QLayoutItem *QDockAreaLayoutInfo::takeAt(int *x, int index)
             if ((*x)++ == index) {
                 item.placeHolderItem = new QPlaceHolderItem(item.widgetItem->widget());
                 QLayoutItem *ret = item.widgetItem;
-                item.widgetItem = 0;
+                item.widgetItem = nullptr;
                 if (item.size != -1)
                     item.flags |= QDockAreaLayoutItem::KeepSize;
                 return ret;
             }
         }
     }
-    return 0;
+    return nullptr;
 }
 
 void QDockAreaLayoutInfo::deleteAllLayoutItems()
@@ -1770,7 +1770,7 @@ void QDockAreaLayoutInfo::deleteAllLayoutItems()
             item.subinfo->deleteAllLayoutItems();
         } else {
             delete item.widgetItem;
-            item.widgetItem = 0;
+            item.widgetItem = nullptr;
         }
     }
 }
@@ -1801,7 +1801,7 @@ void QDockAreaLayoutInfo::saveState(QDataStream &stream) const
 
     for (int i = 0; i < item_list.count(); ++i) {
         const QDockAreaLayoutItem &item = item_list.at(i);
-        if (item.widgetItem != 0) {
+        if (item.widgetItem != nullptr) {
             stream << (uchar) WidgetMarker;
             QWidget *w = item.widgetItem->widget();
             QString name = w->objectName();
@@ -1825,7 +1825,7 @@ void QDockAreaLayoutInfo::saveState(QDataStream &stream) const
                 stream << item.pos << item.size << pick(o, item.minimumSize())
                         << pick(o, item.maximumSize());
             }
-        } else if (item.placeHolderItem != 0) {
+        } else if (item.placeHolderItem != nullptr) {
             stream << (uchar) WidgetMarker;
             stream << item.placeHolderItem->objectName;
             uchar flags = 0;
@@ -1840,7 +1840,7 @@ void QDockAreaLayoutInfo::saveState(QDataStream &stream) const
             } else {
                 stream << item.pos << item.size << (int)0 << (int)0;
             }
-        } else if (item.subinfo != 0) {
+        } else if (item.subinfo != nullptr) {
             stream << (uchar) SequenceMarker << item.pos << item.size << pick(o, item.minimumSize()) << pick(o, item.maximumSize());
             item.subinfo->saveState(stream);
         }
@@ -1894,7 +1894,7 @@ bool QDockAreaLayoutInfo::restoreState(QDataStream &stream, QList<QDockWidget*>
                 continue;
             }
 
-            QDockWidget *widget = 0;
+            QDockWidget *widget = nullptr;
             for (int j = 0; j < widgets.count(); ++j) {
                 if (widgets.at(j)->objectName() == name) {
                     widget = widgets.takeAt(j);
@@ -1902,7 +1902,7 @@ bool QDockAreaLayoutInfo::restoreState(QDataStream &stream, QList<QDockWidget*>
                 }
             }
 
-            if (widget == 0) {
+            if (widget == nullptr) {
                 QPlaceHolderItem *placeHolder = new QPlaceHolderItem;
                 QDockAreaLayoutItem item(placeHolder);
 
@@ -2081,7 +2081,7 @@ bool QDockAreaLayoutInfo::updateTabBar() const
 
     QDockAreaLayoutInfo *that = const_cast<QDockAreaLayoutInfo*>(this);
 
-    if (that->tabBar == 0) {
+    if (that->tabBar == nullptr) {
         that->tabBar = mainWindowLayout()->getTabBar();
         that->tabBar->setShape(static_cast<QTabBar::Shape>(tabBarShape));
         that->tabBar->setDrawBase(true);
@@ -2101,7 +2101,7 @@ bool QDockAreaLayoutInfo::updateTabBar() const
             gap = true;
             continue;
         }
-        if (item.widgetItem == 0)
+        if (item.widgetItem == nullptr)
             continue;
 
         QDockWidget *dw = qobject_cast<QDockWidget*>(item.widgetItem->widget());
@@ -2155,12 +2155,12 @@ void QDockAreaLayoutInfo::setTabBarShape(int shape)
     if (shape == tabBarShape)
         return;
     tabBarShape = shape;
-    if (tabBar != 0)
+    if (tabBar != nullptr)
         tabBar->setShape(static_cast<QTabBar::Shape>(shape));
 
     for (int i = 0; i < item_list.count(); ++i) {
         QDockAreaLayoutItem &item = item_list[i];
-        if (item.subinfo != 0)
+        if (item.subinfo != nullptr)
             item.subinfo->setTabBarShape(shape);
     }
 }
@@ -2192,7 +2192,7 @@ QSet<QTabBar*> QDockAreaLayoutInfo::usedTabBars() const
 
     for (int i = 0; i < item_list.count(); ++i) {
         const QDockAreaLayoutItem &item = item_list.at(i);
-        if (item.subinfo != 0)
+        if (item.subinfo != nullptr)
             result += item.subinfo->usedTabBars();
     }
 
@@ -2212,7 +2212,7 @@ QSet<QWidget*> QDockAreaLayoutInfo::usedSeparatorWidgets() const
 
     for (int i = 0; i < item_list.count(); ++i) {
         const QDockAreaLayoutItem &item = item_list.at(i);
-        if (item.subinfo != 0)
+        if (item.subinfo != nullptr)
             result += item.subinfo->usedSeparatorWidgets();
     }
 
@@ -2277,7 +2277,7 @@ void QDockAreaLayoutInfo::moveTab(int from, int to)
 QDockAreaLayout::QDockAreaLayout(QMainWindow *win) : fallbackToSizeHints(true)
 {
     mainWindow = win;
-    sep = win->style()->pixelMetric(QStyle::PM_DockWidgetSeparatorExtent, 0, win);
+    sep = win->style()->pixelMetric(QStyle::PM_DockWidgetSeparatorExtent, nullptr, win);
 #if QT_CONFIG(tabbar)
     const int tabShape = QTabBar::RoundedSouth;
 #else
@@ -2291,7 +2291,7 @@ QDockAreaLayout::QDockAreaLayout(QMainWindow *win) : fallbackToSizeHints(true)
         = QDockAreaLayoutInfo(&sep, QInternal::TopDock, Qt::Horizontal, tabShape, win);
     docks[QInternal::BottomDock]
         = QDockAreaLayoutInfo(&sep, QInternal::BottomDock, Qt::Horizontal, tabShape, win);
-    centralWidgetItem = 0;
+    centralWidgetItem = nullptr;
 
 
     corners[Qt::TopLeftCorner] = Qt::TopDockWidgetArea;
@@ -2491,7 +2491,7 @@ QDockAreaLayoutInfo *QDockAreaLayout::info(QWidget *widget)
             return result;
     }
 
-    return 0;
+    return nullptr;
 }
 
 QDockAreaLayoutInfo *QDockAreaLayout::info(const QList<int> &path)
@@ -2623,7 +2623,7 @@ void QDockAreaLayout::getGrid(QVector<QLayoutStruct> *_ver_struct_list,
     QSize center_hint(0, 0);
     QSize center_min(0, 0);
     QSize center_max(0, 0);
-    const bool have_central = centralWidgetItem != 0 && !centralWidgetItem->isEmpty();
+    const bool have_central = centralWidgetItem != nullptr && !centralWidgetItem->isEmpty();
     if (have_central) {
         center_hint = centralWidgetRect.size();
         if (!center_hint.isValid())
@@ -2670,7 +2670,7 @@ void QDockAreaLayout::getGrid(QVector<QLayoutStruct> *_ver_struct_list,
     QSize bottom_max = docks[QInternal::BottomDock].maximumSize();
     bottom_hint = bottom_hint.boundedTo(bottom_max).expandedTo(bottom_min);
 
-    if (_ver_struct_list != 0) {
+    if (_ver_struct_list != nullptr) {
         QVector<QLayoutStruct> &ver_struct_list = *_ver_struct_list;
         ver_struct_list.resize(3);
 
@@ -2732,7 +2732,7 @@ void QDockAreaLayout::getGrid(QVector<QLayoutStruct> *_ver_struct_list,
             ver_struct_list[1].maximumSize = QWIDGETSIZE_MAX;
     }
 
-    if (_hor_struct_list != 0) {
+    if (_hor_struct_list != nullptr) {
         QVector<QLayoutStruct> &hor_struct_list = *_hor_struct_list;
         hor_struct_list.resize(3);
 
@@ -2803,7 +2803,7 @@ void QDockAreaLayout::setGrid(QVector<QLayoutStruct> *ver_struct_list,
 
     if (!docks[QInternal::TopDock].isEmpty()) {
         QRect r = docks[QInternal::TopDock].rect;
-        if (hor_struct_list != 0) {
+        if (hor_struct_list != nullptr) {
             r.setLeft(corners[Qt::TopLeftCorner] == Qt::TopDockWidgetArea
                 || docks[QInternal::LeftDock].isEmpty()
                 ? rect.left() : hor_struct_list->at(1).pos);
@@ -2811,7 +2811,7 @@ void QDockAreaLayout::setGrid(QVector<QLayoutStruct> *ver_struct_list,
                 || docks[QInternal::RightDock].isEmpty()
                 ? rect.right() : hor_struct_list->at(2).pos - sep - 1);
         }
-        if (ver_struct_list != 0) {
+        if (ver_struct_list != nullptr) {
             r.setTop(rect.top());
             r.setBottom(ver_struct_list->at(1).pos - sep - 1);
         }
@@ -2823,7 +2823,7 @@ void QDockAreaLayout::setGrid(QVector<QLayoutStruct> *ver_struct_list,
 
     if (!docks[QInternal::BottomDock].isEmpty()) {
         QRect r = docks[QInternal::BottomDock].rect;
-        if (hor_struct_list != 0) {
+        if (hor_struct_list != nullptr) {
             r.setLeft(corners[Qt::BottomLeftCorner] == Qt::BottomDockWidgetArea
                         || docks[QInternal::LeftDock].isEmpty()
                             ? rect.left() : hor_struct_list->at(1).pos);
@@ -2831,7 +2831,7 @@ void QDockAreaLayout::setGrid(QVector<QLayoutStruct> *ver_struct_list,
                         || docks[QInternal::RightDock].isEmpty()
                             ? rect.right() : hor_struct_list->at(2).pos - sep - 1);
         }
-        if (ver_struct_list != 0) {
+        if (ver_struct_list != nullptr) {
             r.setTop(ver_struct_list->at(2).pos);
             r.setBottom(rect.bottom());
         }
@@ -2843,11 +2843,11 @@ void QDockAreaLayout::setGrid(QVector<QLayoutStruct> *ver_struct_list,
 
     if (!docks[QInternal::LeftDock].isEmpty()) {
         QRect r = docks[QInternal::LeftDock].rect;
-        if (hor_struct_list != 0) {
+        if (hor_struct_list != nullptr) {
             r.setLeft(rect.left());
             r.setRight(hor_struct_list->at(1).pos - sep - 1);
         }
-        if (ver_struct_list != 0) {
+        if (ver_struct_list != nullptr) {
             r.setTop(corners[Qt::TopLeftCorner] == Qt::LeftDockWidgetArea
                 || docks[QInternal::TopDock].isEmpty()
                 ? rect.top() : ver_struct_list->at(1).pos);
@@ -2863,11 +2863,11 @@ void QDockAreaLayout::setGrid(QVector<QLayoutStruct> *ver_struct_list,
 
     if (!docks[QInternal::RightDock].isEmpty()) {
         QRect r = docks[QInternal::RightDock].rect;
-        if (hor_struct_list != 0) {
+        if (hor_struct_list != nullptr) {
             r.setLeft(hor_struct_list->at(2).pos);
             r.setRight(rect.right());
         }
-        if (ver_struct_list != 0) {
+        if (ver_struct_list != nullptr) {
             r.setTop(corners[Qt::TopRightCorner] == Qt::RightDockWidgetArea
                         || docks[QInternal::TopDock].isEmpty()
                             ? rect.top() : ver_struct_list->at(1).pos);
@@ -2881,11 +2881,11 @@ void QDockAreaLayout::setGrid(QVector<QLayoutStruct> *ver_struct_list,
 
     // center ---------------------------------------------------
 
-    if (hor_struct_list != 0) {
+    if (hor_struct_list != nullptr) {
         centralWidgetRect.setLeft(hor_struct_list->at(1).pos);
         centralWidgetRect.setWidth(hor_struct_list->at(1).size);
     }
-    if (ver_struct_list != 0) {
+    if (ver_struct_list != nullptr) {
         centralWidgetRect.setTop(ver_struct_list->at(1).pos);
         centralWidgetRect.setHeight(ver_struct_list->at(1).size);
     }
@@ -2919,7 +2919,7 @@ QSize QDockAreaLayout::sizeHint() const
     int top_sep = 0;
     int bottom_sep = 0;
 
-    if (centralWidgetItem != 0) {
+    if (centralWidgetItem != nullptr) {
         left_sep = docks[QInternal::LeftDock].isEmpty() ? 0 : sep;
         right_sep = docks[QInternal::RightDock].isEmpty() ? 0 : sep;
         top_sep = docks[QInternal::TopDock].isEmpty() ? 0 : sep;
@@ -2930,7 +2930,7 @@ QSize QDockAreaLayout::sizeHint() const
     QSize right = docks[QInternal::RightDock].sizeHint() + QSize(right_sep, 0);
     QSize top = docks[QInternal::TopDock].sizeHint() + QSize(0, top_sep);
     QSize bottom = docks[QInternal::BottomDock].sizeHint() + QSize(0, bottom_sep);
-    QSize center = centralWidgetItem == 0 ? QSize(0, 0) : centralWidgetItem->sizeHint();
+    QSize center = centralWidgetItem == nullptr ? QSize(0, 0) : centralWidgetItem->sizeHint();
 
     int row1 = top.width();
     int row2 = left.width() + center.width() + right.width();
@@ -2969,7 +2969,7 @@ QSize QDockAreaLayout::minimumSize() const
     int top_sep = 0;
     int bottom_sep = 0;
 
-    if (centralWidgetItem != 0) {
+    if (centralWidgetItem != nullptr) {
         left_sep = docks[QInternal::LeftDock].isEmpty() ? 0 : sep;
         right_sep = docks[QInternal::RightDock].isEmpty() ? 0 : sep;
         top_sep = docks[QInternal::TopDock].isEmpty() ? 0 : sep;
@@ -2980,7 +2980,7 @@ QSize QDockAreaLayout::minimumSize() const
     QSize right = docks[QInternal::RightDock].minimumSize() + QSize(right_sep, 0);
     QSize top = docks[QInternal::TopDock].minimumSize() + QSize(0, top_sep);
     QSize bottom = docks[QInternal::BottomDock].minimumSize() + QSize(0, bottom_sep);
-    QSize center = centralWidgetItem == 0 ? QSize(0, 0) : centralWidgetItem->minimumSize();
+    QSize center = centralWidgetItem == nullptr ? QSize(0, 0) : centralWidgetItem->minimumSize();
 
     int row1 = top.width();
     int row2 = left.width() + center.width() + right.width();
@@ -3040,7 +3040,7 @@ QRect QDockAreaLayout::constrainedRect(QRect rect, QWidget* widget)
 
 bool QDockAreaLayout::restoreDockWidget(QDockWidget *dockWidget)
 {
-    QDockAreaLayoutItem *item = 0;
+    QDockAreaLayoutItem *item = nullptr;
     const auto groups =
             mainWindow->findChildren<QDockWidgetGroupWindow *>(QString(), Qt::FindDirectChildrenOnly);
     for (QDockWidgetGroupWindow *dwgw : groups) {
@@ -3059,7 +3059,7 @@ bool QDockAreaLayout::restoreDockWidget(QDockWidget *dockWidget)
     }
 
     QPlaceHolderItem *placeHolder = item->placeHolderItem;
-    Q_ASSERT(placeHolder != 0);
+    Q_ASSERT(placeHolder != nullptr);
 
     item->widgetItem = new QDockWidgetItem(dockWidget);
 
@@ -3069,7 +3069,7 @@ bool QDockAreaLayout::restoreDockWidget(QDockWidget *dockWidget)
     }
     dockWidget->setVisible(!placeHolder->hidden);
 
-    item->placeHolderItem = 0;
+    item->placeHolderItem = nullptr;
     delete placeHolder;
 
     return true;
@@ -3116,7 +3116,7 @@ void QDockAreaLayout::tabifyDockWidget(QDockWidget *first, QDockWidget *second)
         return;
 
     QDockAreaLayoutInfo *info = this->info(path);
-    Q_ASSERT(info != 0);
+    Q_ASSERT(info != nullptr);
     info->tab(path.last(), new QDockWidgetItem(second));
 
     removePlaceHolder(second->objectName());
@@ -3181,7 +3181,7 @@ void QDockAreaLayout::splitDockWidget(QDockWidget *after,
         return;
 
     QDockAreaLayoutInfo *info = this->info(path);
-    Q_ASSERT(info != 0);
+    Q_ASSERT(info != nullptr);
     info->split(path.last(), orientation, new QDockWidgetItem(dockWidget));
 
     removePlaceHolder(dockWidget->objectName());
@@ -3193,7 +3193,7 @@ void QDockAreaLayout::apply(bool animate)
 
     for (int i = 0; i < QInternal::DockCount; ++i)
         docks[i].apply(animate);
-    if (centralWidgetItem != 0 && !centralWidgetItem->isEmpty()) {
+    if (centralWidgetItem != nullptr && !centralWidgetItem->isEmpty()) {
         widgetAnimator.animate(centralWidgetItem->widget(), centralWidgetRect,
                                 animate);
     }
@@ -3255,9 +3255,9 @@ int QDockAreaLayout::separatorMove(const QList<int> &separator, const QPoint &or
     QVector<QLayoutStruct> list;
 
     if (index == QInternal::LeftDock || index == QInternal::RightDock)
-        getGrid(0, &list);
+        getGrid(nullptr, &list);
     else
-        getGrid(&list, 0);
+        getGrid(&list, nullptr);
 
     int sep_index = index == QInternal::LeftDock || index == QInternal::TopDock
                         ? 0 : 1;
@@ -3271,9 +3271,9 @@ int QDockAreaLayout::separatorMove(const QList<int> &separator, const QPoint &or
     fallbackToSizeHints = false;
 
     if (index == QInternal::LeftDock || index == QInternal::RightDock)
-        setGrid(0, &list);
+        setGrid(nullptr, &list);
     else
-        setGrid(&list, 0);
+        setGrid(&list, nullptr);
 
     apply(false);
 
@@ -3330,7 +3330,7 @@ void QDockAreaLayout::updateSeparatorWidgets() const
 
 QLayoutItem *QDockAreaLayout::itemAt(int *x, int index) const
 {
-    Q_ASSERT(x != 0);
+    Q_ASSERT(x != nullptr);
 
     for (int i = 0; i < QInternal::DockCount; ++i) {
         const QDockAreaLayoutInfo &dock = docks[i];
@@ -3341,12 +3341,12 @@ QLayoutItem *QDockAreaLayout::itemAt(int *x, int index) const
     if (centralWidgetItem && (*x)++ == index)
         return centralWidgetItem;
 
-    return 0;
+    return nullptr;
 }
 
 QLayoutItem *QDockAreaLayout::takeAt(int *x, int index)
 {
-    Q_ASSERT(x != 0);
+    Q_ASSERT(x != nullptr);
 
     for (int i = 0; i < QInternal::DockCount; ++i) {
         QDockAreaLayoutInfo &dock = docks[i];
@@ -3356,11 +3356,11 @@ QLayoutItem *QDockAreaLayout::takeAt(int *x, int index)
 
     if (centralWidgetItem && (*x)++ == index) {
         QLayoutItem *ret = centralWidgetItem;
-        centralWidgetItem = 0;
+        centralWidgetItem = nullptr;
         return ret;
     }
 
-    return 0;
+    return nullptr;
 }
 
 void QDockAreaLayout::deleteAllLayoutItems()
@@ -3399,7 +3399,7 @@ QSet<QWidget*> QDockAreaLayout::usedSeparatorWidgets() const
 QRect QDockAreaLayout::gapRect(const QList<int> &path) const
 {
     const QDockAreaLayoutInfo *info = this->info(path);
-    if (info == 0)
+    if (info == nullptr)
         return QRect();
     int index = path.last();
     if (index < 0 || index >= info->item_list.count())
@@ -3419,7 +3419,7 @@ void QDockAreaLayout::keepSize(QDockWidget *w)
 
 void QDockAreaLayout::styleChangedEvent()
 {
-    sep = mainWindow->style()->pixelMetric(QStyle::PM_DockWidgetSeparatorExtent, 0, mainWindow);
+    sep = mainWindow->style()->pixelMetric(QStyle::PM_DockWidgetSeparatorExtent, nullptr, mainWindow);
     if (isValid())
         fitLayout();
 }
diff --git a/src/widgets/widgets/qdockwidget.cpp b/src/widgets/widgets/qdockwidget.cpp
index bcbd3dd2d4..299e5da8d3 100644
--- a/src/widgets/widgets/qdockwidget.cpp
+++ b/src/widgets/widgets/qdockwidget.cpp
@@ -197,7 +197,7 @@ QSize QDockWidgetTitleButton::sizeHint() const
 {
     ensurePolished();
 
-    int size = 2*style()->pixelMetric(QStyle::PM_DockWidgetTitleBarButtonMargin, 0, this);
+    int size = 2*style()->pixelMetric(QStyle::PM_DockWidgetTitleBarButtonMargin, nullptr, this);
     if (!icon().isNull()) {
         const QSize sz = icon().actualSize(dockButtonIconSize());
         size += qMax(sz.width(), sz.height());
@@ -226,7 +226,7 @@ void QDockWidgetTitleButton::paintEvent(QPaintEvent *)
     opt.init(this);
     opt.state |= QStyle::State_AutoRaise;
 
-    if (style()->styleHint(QStyle::SH_DockWidget_ButtonsHaveFrame, 0, this))
+    if (style()->styleHint(QStyle::SH_DockWidget_ButtonsHaveFrame, nullptr, this))
     {
         if (isEnabled() && underMouse() && !isChecked() && !isDown())
             opt.state |= QStyle::State_Raised;
@@ -311,12 +311,12 @@ QLayoutItem *QDockWidgetLayout::itemAt(int index) const
     int cnt = 0;
     for (int i = 0; i < item_list.count(); ++i) {
         QLayoutItem *item = item_list.at(i);
-        if (item == 0)
+        if (item == nullptr)
             continue;
         if (index == cnt++)
             return item;
     }
-    return 0;
+    return nullptr;
 }
 
 QLayoutItem *QDockWidgetLayout::takeAt(int index)
@@ -324,7 +324,7 @@ QLayoutItem *QDockWidgetLayout::takeAt(int index)
     int j = 0;
     for (int i = 0; i < item_list.count(); ++i) {
         QLayoutItem *item = item_list.at(i);
-        if (item == 0)
+        if (item == nullptr)
             continue;
         if (index == j) {
             item_list[i] = 0;
@@ -333,7 +333,7 @@ QLayoutItem *QDockWidgetLayout::takeAt(int index)
         }
         ++j;
     }
-    return 0;
+    return nullptr;
 }
 
 int QDockWidgetLayout::count() const
@@ -362,7 +362,7 @@ QSize QDockWidgetLayout::sizeFromContent(const QSize &content, bool floating) co
     const bool nativeDeco = nativeWindowDeco(floating);
 
     int fw = floating && !nativeDeco
-            ? w->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, 0, w)
+            ? w->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, nullptr, w)
             : 0;
 
     const int th = titleHeight();
@@ -394,7 +394,7 @@ QSize QDockWidgetLayout::sizeFromContent(const QSize &content, bool floating) co
 
     uint explicitMin = 0;
     uint explicitMax = 0;
-    if (w->d_func()->extra != 0) {
+    if (w->d_func()->extra != nullptr) {
         explicitMin = w->d_func()->extra->explicitMinSize;
         explicitMax = w->d_func()->extra->explicitMaxSize;
     }
@@ -448,7 +448,7 @@ QSize QDockWidgetLayout::minimumSize() const
 QWidget *QDockWidgetLayout::widgetForRole(Role r) const
 {
     QLayoutItem *item = item_list.at(r);
-    return item == 0 ? 0 : item->widget();
+    return item == nullptr ? nullptr : item->widget();
 }
 
 QLayoutItem *QDockWidgetLayout::itemForRole(Role r) const
@@ -459,12 +459,12 @@ QLayoutItem *QDockWidgetLayout::itemForRole(Role r) const
 void QDockWidgetLayout::setWidgetForRole(Role r, QWidget *w)
 {
     QWidget *old = widgetForRole(r);
-    if (old != 0) {
+    if (old != nullptr) {
         old->hide();
         removeWidget(old);
     }
 
-    if (w != 0) {
+    if (w != nullptr) {
         addChildWidget(w);
         item_list[r] = new QWidgetItemV2(w);
         w->show();
@@ -505,8 +505,8 @@ int QDockWidgetLayout::minimumTitleWidth() const
 
     int titleHeight = this->titleHeight();
 
-    int mw = q->style()->pixelMetric(QStyle::PM_DockWidgetTitleMargin, 0, q);
-    int fw = q->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, 0, q);
+    int mw = q->style()->pixelMetric(QStyle::PM_DockWidgetTitleMargin, nullptr, q);
+    int fw = q->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, nullptr, q);
 
     return pick(verticalTitleBar, closeSize)
             + pick(verticalTitleBar, floatSize)
@@ -531,7 +531,7 @@ int QDockWidgetLayout::titleHeight() const
                             perp(verticalTitleBar, floatSize));
 
     QFontMetrics titleFontMetrics = q->fontMetrics();
-    int mw = q->style()->pixelMetric(QStyle::PM_DockWidgetTitleMargin, 0, q);
+    int mw = q->style()->pixelMetric(QStyle::PM_DockWidgetTitleMargin, nullptr, q);
 
     return qMax(buttonHeight + 2, titleFontMetrics.height() + 2*mw);
 }
@@ -543,7 +543,7 @@ void QDockWidgetLayout::setGeometry(const QRect &geometry)
     bool nativeDeco = nativeWindowDeco();
 
     int fw = q->isFloating() && !nativeDeco
-            ? q->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, 0, q)
+            ? q->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, nullptr, q)
             : 0;
 
     if (nativeDeco) {
@@ -730,7 +730,7 @@ void QDockWidgetPrivate::updateButtons()
     QStyleOptionDockWidget opt;
     q->initStyleOption(&opt);
 
-    bool customTitleBar = dwLayout->widgetForRole(QDockWidgetLayout::TitleBar) != 0;
+    bool customTitleBar = dwLayout->widgetForRole(QDockWidgetLayout::TitleBar) != nullptr;
     bool nativeDeco = dwLayout->nativeWindowDeco();
     bool hideButtons = nativeDeco || customTitleBar;
 
@@ -777,18 +777,18 @@ void QDockWidgetPrivate::initDrag(const QPoint &pos, bool nca)
 {
     Q_Q(QDockWidget);
 
-    if (state != 0)
+    if (state != nullptr)
         return;
 
     QMainWindowLayout *layout = qt_mainwindow_layout_from_dock(q);
-    Q_ASSERT(layout != 0);
-    if (layout->pluggingWidget != 0) // the main window is animating a docking operation
+    Q_ASSERT(layout != nullptr);
+    if (layout->pluggingWidget != nullptr) // the main window is animating a docking operation
         return;
 
     state = new QDockWidgetPrivate::DragState;
     state->pressPos = pos;
     state->dragging = false;
-    state->widgetItem = 0;
+    state->widgetItem = nullptr;
     state->ownWidgetItem = false;
     state->nca = nca;
     state->ctrlDrag = false;
@@ -804,14 +804,14 @@ void QDockWidgetPrivate::startDrag(bool group)
 {
     Q_Q(QDockWidget);
 
-    if (state == 0 || state->dragging)
+    if (state == nullptr || state->dragging)
         return;
 
     QMainWindowLayout *layout = qt_mainwindow_layout_from_dock(q);
-    Q_ASSERT(layout != 0);
+    Q_ASSERT(layout != nullptr);
 
     state->widgetItem = layout->unplug(q, group);
-    if (state->widgetItem == 0) {
+    if (state->widgetItem == nullptr) {
         /* I have a QMainWindow parent, but I was never inserted with
             QMainWindow::addDockWidget, so the QMainWindowLayout has no
             widget item for me. :( I have to create it myself, and then
@@ -838,7 +838,7 @@ void QDockWidgetPrivate::startDrag(bool group)
 void QDockWidgetPrivate::endDrag(bool abort)
 {
     Q_Q(QDockWidget);
-    Q_ASSERT(state != 0);
+    Q_ASSERT(state != nullptr);
 
     q->releaseMouse();
 
@@ -881,7 +881,7 @@ void QDockWidgetPrivate::endDrag(bool abort)
         }
     }
     delete state;
-    state = 0;
+    state = nullptr;
 }
 
 void QDockWidgetPrivate::setResizerActive(bool active)
@@ -900,7 +900,7 @@ bool QDockWidgetPrivate::isAnimating() const
     Q_Q(const QDockWidget);
 
     QMainWindowLayout *mainWinLayout = qt_mainwindow_layout_from_dock(q);
-    if (mainWinLayout == 0)
+    if (mainWinLayout == nullptr)
         return false;
 
     return (const void*)mainWinLayout->pluggingWidget == (const void*)q;
@@ -925,7 +925,7 @@ bool QDockWidgetPrivate::mousePressEvent(QMouseEvent *event)
             // is not (but allow moving if the window is floating)
             (!hasFeature(this, QDockWidget::DockWidgetMovable) && !q->isFloating()) ||
             (qobject_cast<QMainWindow*>(parent) == 0 && !floatingTab) ||
-            isAnimating() || state != 0) {
+            isAnimating() || state != nullptr) {
             return false;
         }
 
@@ -972,7 +972,7 @@ bool QDockWidgetPrivate::mouseMoveEvent(QMouseEvent *event)
     QMainWindowLayout *mwlayout = qt_mainwindow_layout_from_dock(q);
     if (!dwlayout->nativeWindowDeco()) {
         if (!state->dragging
-            && mwlayout->pluggingWidget == 0
+            && mwlayout->pluggingWidget == nullptr
             && (event->pos() - state->pressPos).manhattanLength()
                 > QApplication::startDragDistance()) {
             startDrag();
@@ -1019,7 +1019,7 @@ void QDockWidgetPrivate::nonClientAreaMouseEvent(QMouseEvent *event)
 {
     Q_Q(QDockWidget);
 
-    int fw = q->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, 0, q);
+    int fw = q->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, nullptr, q);
 
     QWidget *tl = q->topLevelWidget();
     QRect geo = tl->geometry();
@@ -1035,21 +1035,21 @@ void QDockWidgetPrivate::nonClientAreaMouseEvent(QMouseEvent *event)
         case QEvent::NonClientAreaMouseButtonPress:
             if (!titleRect.contains(event->globalPos()))
                 break;
-            if (state != 0)
+            if (state != nullptr)
                 break;
             if (qobject_cast<QMainWindow*>(parent) == 0 && qobject_cast<QDockWidgetGroupWindow*>(parent) == 0)
                 break;
             if (isAnimating())
                 break;
             initDrag(event->pos(), true);
-            if (state == 0)
+            if (state == nullptr)
                 break;
             state->ctrlDrag = (event->modifiers() & Qt::ControlModifier) ||
                               (!hasFeature(this, QDockWidget::DockWidgetMovable) && q->isFloating());
             startDrag();
             break;
         case QEvent::NonClientAreaMouseMove:
-            if (state == 0 || !state->dragging)
+            if (state == nullptr || !state->dragging)
                 break;
 
 #ifndef Q_OS_MAC
@@ -1085,7 +1085,7 @@ void QDockWidgetPrivate::moveEvent(QMoveEvent *event)
 {
     Q_Q(QDockWidget);
 
-    if (state == 0 || !state->dragging || !state->nca)
+    if (state == nullptr || !state->dragging || !state->nca)
         return;
 
     if (!q->isWindow() && qobject_cast<QDockWidgetGroupWindow*>(parent) == 0)
@@ -1098,7 +1098,7 @@ void QDockWidgetPrivate::moveEvent(QMoveEvent *event)
         return;
 
     QMainWindowLayout *layout = qt_mainwindow_layout_from_dock(q);
-    Q_ASSERT(layout != 0);
+    Q_ASSERT(layout != nullptr);
 
     QPoint globalMousePos = event->pos() + state->pressPos;
     layout->hover(state->widgetItem, globalMousePos);
@@ -1384,7 +1384,7 @@ void QDockWidget::setFloating(bool floating)
     Q_D(QDockWidget);
 
     // the initial click of a double-click may have started a drag...
-    if (d->state != 0)
+    if (d->state != nullptr)
         d->endDrag(true);
 
     QRect r = d->undockedGeometry;
@@ -1479,7 +1479,7 @@ void QDockWidget::paintEvent(QPaintEvent *event)
 
     QDockWidgetLayout *layout
         = qobject_cast<QDockWidgetLayout*>(this->layout());
-    bool customTitleBar = layout->widgetForRole(QDockWidgetLayout::TitleBar) != 0;
+    bool customTitleBar = layout->widgetForRole(QDockWidgetLayout::TitleBar) != nullptr;
     bool nativeDeco = layout->nativeWindowDeco();
 
     if (!nativeDeco && !customTitleBar) {
@@ -1516,7 +1516,7 @@ bool QDockWidget::event(QEvent *event)
     switch (event->type()) {
 #ifndef QT_NO_ACTION
     case QEvent::Hide:
-        if (layout != 0)
+        if (layout != nullptr)
             layout->keepSize(this);
         d->toggleViewAction->setChecked(false);
         emit visibilityChanged(false);
@@ -1542,12 +1542,12 @@ bool QDockWidget::event(QEvent *event)
         break;
     case QEvent::ZOrderChange: {
         bool onTop = false;
-        if (win != 0) {
+        if (win != nullptr) {
             const QObjectList &siblings = win->children();
             onTop = siblings.count() > 0 && siblings.last() == (QObject*)this;
         }
 #if QT_CONFIG(tabbar)
-        if (!isFloating() && layout != 0 && onTop)
+        if (!isFloating() && layout != nullptr && onTop)
             layout->raise(this);
 #endif
         break;
@@ -1591,7 +1591,7 @@ bool QDockWidget::event(QEvent *event)
         break;
     case QEvent::Resize:
         // if the mainwindow is plugging us, we don't want to update undocked geometry
-        if (isFloating() && layout != 0 && layout->pluggingWidget != this)
+        if (isFloating() && layout != nullptr && layout->pluggingWidget != this)
             d->undockedGeometry = geometry();
 
         // Usually the window won't get resized while it's being moved, but it can happen,
diff --git a/src/widgets/widgets/qeffects.cpp b/src/widgets/widgets/qeffects.cpp
index e69366d7c8..ee4095cb36 100644
--- a/src/widgets/widgets/qeffects.cpp
+++ b/src/widgets/widgets/qeffects.cpp
@@ -93,7 +93,7 @@ private:
     QElapsedTimer checkTime;
 };
 
-static QAlphaWidget* q_blend = 0;
+static QAlphaWidget* q_blend = nullptr;
 
 /*
   Constructs a QAlphaWidget.
@@ -285,7 +285,7 @@ void QAlphaWidget::render()
                 lower();
             }
         }
-        q_blend = 0;
+        q_blend = nullptr;
         deleteLater();
     } else {
         alphaBlend();
@@ -377,13 +377,13 @@ private:
     QPixmap pm;
 };
 
-static QRollEffect* q_roll = 0;
+static QRollEffect* q_roll = nullptr;
 
 /*
   Construct a QRollEffect widget.
 */
 QRollEffect::QRollEffect(QWidget* w, Qt::WindowFlags f, DirFlags orient)
-    : QWidget(0, f), orientation(orient)
+    : QWidget(nullptr, f), orientation(orient)
 {
 #ifndef Q_OS_WIN
     setEnabled(false);
@@ -550,7 +550,7 @@ void QRollEffect::scroll()
                 lower();
             }
         }
-        q_roll = 0;
+        q_roll = nullptr;
         deleteLater();
     }
 }
@@ -563,7 +563,7 @@ void qScrollEffect(QWidget* w, QEffects::DirFlags orient, int time)
 {
     if (q_roll) {
         q_roll->deleteLater();
-        q_roll = 0;
+        q_roll = nullptr;
     }
 
     if (!w)
@@ -585,7 +585,7 @@ void qFadeEffect(QWidget* w, int time)
 {
     if (q_blend) {
         q_blend->deleteLater();
-        q_blend = 0;
+        q_blend = nullptr;
     }
 
     if (!w)
diff --git a/src/widgets/widgets/qfocusframe.cpp b/src/widgets/widgets/qfocusframe.cpp
index ee24e92c7e..4d64c24db3 100644
--- a/src/widgets/widgets/qfocusframe.cpp
+++ b/src/widgets/widgets/qfocusframe.cpp
@@ -55,8 +55,8 @@ class QFocusFramePrivate : public QWidgetPrivate
     bool showFrameAboveWidget;
 public:
     QFocusFramePrivate() {
-        widget = 0;
-        frameParent = 0;
+        widget = nullptr;
+        frameParent = nullptr;
         sendChildEvents = false;
         showFrameAboveWidget = false;
     }
@@ -159,7 +159,7 @@ QFocusFrame::QFocusFrame(QWidget *parent)
     setAttribute(Qt::WA_TransparentForMouseEvents);
     setFocusPolicy(Qt::NoFocus);
     setAttribute(Qt::WA_NoChildEventsForParent, true);
-    setAttribute(Qt::WA_AcceptDrops, style()->styleHint(QStyle::SH_FocusFrame_AboveWidget, 0, this));
+    setAttribute(Qt::WA_AcceptDrops, style()->styleHint(QStyle::SH_FocusFrame_AboveWidget, nullptr, this));
 }
 
 /*!
@@ -184,7 +184,7 @@ QFocusFrame::setWidget(QWidget *widget)
 {
     Q_D(QFocusFrame);
 
-    if (style()->styleHint(QStyle::SH_FocusFrame_AboveWidget, 0, this))
+    if (style()->styleHint(QStyle::SH_FocusFrame_AboveWidget, nullptr, this))
         d->showFrameAboveWidget = true;
     else
         d->showFrameAboveWidget = false;
@@ -205,7 +205,7 @@ QFocusFrame::setWidget(QWidget *widget)
         d->widget = widget;
         d->widget->installEventFilter(this);
         QWidget *p = widget->parentWidget();
-        QWidget *prev = 0;
+        QWidget *prev = nullptr;
         if (d->showFrameAboveWidget) {
             // Find the right parent for the focus frame.
             while (p) {
@@ -231,7 +231,7 @@ QFocusFrame::setWidget(QWidget *widget)
         }
         d->update();
     } else {
-        d->widget = 0;
+        d->widget = nullptr;
         hide();
     }
 }
@@ -290,7 +290,7 @@ QFocusFrame::eventFilter(QObject *o, QEvent *e)
         case QEvent::ParentChange:
             if (d->showFrameAboveWidget) {
                 QWidget *w = d->widget;
-                setWidget(0);
+                setWidget(nullptr);
                 setWidget(w);
             } else {
                 d->update();
@@ -304,13 +304,13 @@ QFocusFrame::eventFilter(QObject *o, QEvent *e)
             setPalette(d->widget->palette());
             break;
         case QEvent::ZOrderChange:
-            if (style()->styleHint(QStyle::SH_FocusFrame_AboveWidget, 0, this))
+            if (style()->styleHint(QStyle::SH_FocusFrame_AboveWidget, nullptr, this))
                 raise();
             else
                 stackUnder(d->widget);
             break;
         case QEvent::Destroy:
-            setWidget(0);
+            setWidget(nullptr);
             break;
         default:
             break;
diff --git a/src/widgets/widgets/qgroupbox.cpp b/src/widgets/widgets/qgroupbox.cpp
index f7fe072302..048fe42948 100644
--- a/src/widgets/widgets/qgroupbox.cpp
+++ b/src/widgets/widgets/qgroupbox.cpp
@@ -424,8 +424,8 @@ void QGroupBoxPrivate::_q_fixFocus(Qt::FocusReason reason)
     Q_Q(QGroupBox);
     QWidget *fw = q->focusWidget();
     if (!fw || fw == q) {
-        QWidget * best = 0;
-        QWidget * candidate = 0;
+        QWidget * best = nullptr;
+        QWidget * candidate = nullptr;
         QWidget * w = q;
         while ((w = w->nextInFocusChain()) != q) {
             if (q->isAncestorOf(w) && (w->focusPolicy() & Qt::TabFocus) == Qt::TabFocus && w->isVisibleTo(q)) {
diff --git a/src/widgets/widgets/qlcdnumber.cpp b/src/widgets/widgets/qlcdnumber.cpp
index 282714843c..3ddada4514 100644
--- a/src/widgets/widgets/qlcdnumber.cpp
+++ b/src/widgets/widgets/qlcdnumber.cpp
@@ -51,7 +51,7 @@ class QLCDNumberPrivate : public QFramePrivate
 public:
     void init();
     void internalSetString(const QString& s);
-    void drawString(const QString& s, QPainter &, QBitArray * = 0, bool = true);
+    void drawString(const QString& s, QPainter &, QBitArray * = nullptr, bool = true);
     //void drawString(const QString &, QPainter &, QBitArray * = 0) const;
     void drawDigit(const QPoint &, QPainter &, int, char, char = ' ');
     void drawSegment(const QPoint &, char, QPainter &, int, bool = false);
@@ -212,7 +212,7 @@ static QString double2string(double num, int base, int ndigits, bool *oflow)
                 *oflow = true;
             return s;
         }
-        s = int2string((int)num, base, ndigits, 0);
+        s = int2string((int)num, base, ndigits, nullptr);
     } else {                                    // decimal base
         int nd = ndigits;
         do {
@@ -706,7 +706,7 @@ void QLCDNumber::paintEvent(QPaintEvent *)
     if (d->smallPoint)
         d->drawString(d->digitStr, p, &d->points, false);
     else
-        d->drawString(d->digitStr, p, 0, false);
+        d->drawString(d->digitStr, p, nullptr, false);
 }
 
 
diff --git a/src/widgets/widgets/qlineedit.cpp b/src/widgets/widgets/qlineedit.cpp
index dc767cdae6..bcd6614ee4 100644
--- a/src/widgets/widgets/qlineedit.cpp
+++ b/src/widgets/widgets/qlineedit.cpp
@@ -446,7 +446,7 @@ void QLineEdit::addAction(QAction *action, ActionPosition position)
 {
     Q_D(QLineEdit);
     QWidget::addAction(action);
-    d->addAction(action, 0, position);
+    d->addAction(action, nullptr, position);
 }
 
 /*!
@@ -640,15 +640,15 @@ void QLineEdit::setCompleter(QCompleter *c)
     if (c == d->control->completer())
         return;
     if (d->control->completer()) {
-        disconnect(d->control->completer(), 0, this, 0);
-        d->control->completer()->setWidget(0);
+        disconnect(d->control->completer(), nullptr, this, nullptr);
+        d->control->completer()->setWidget(nullptr);
         if (d->control->completer()->parent() == this)
             delete d->control->completer();
     }
     d->control->setCompleter(c);
     if (!c)
         return;
-    if (c->widget() == 0)
+    if (c->widget() == nullptr)
         c->setWidget(this);
     if (hasFocus()) {
         QObject::connect(d->control->completer(), SIGNAL(activated(QString)),
@@ -683,7 +683,7 @@ QSize QLineEdit::sizeHint() const
     Q_D(const QLineEdit);
     ensurePolished();
     QFontMetrics fm(font());
-    const int iconSize = style()->pixelMetric(QStyle::PM_SmallIconSize, 0, this);
+    const int iconSize = style()->pixelMetric(QStyle::PM_SmallIconSize, nullptr, this);
     const QMargins tm = d->effectiveTextMargins();
     int h = qMax(fm.height(), qMax(14, iconSize - 2)) + 2 * QLineEditPrivate::verticalMargin
             + tm.top() + tm.bottom()
@@ -1951,7 +1951,7 @@ void QLineEdit::focusOutEvent(QFocusEvent *e)
 #endif
 #if QT_CONFIG(completer)
     if (d->control->completer()) {
-        QObject::disconnect(d->control->completer(), 0, this, 0);
+        QObject::disconnect(d->control->completer(), nullptr, this, nullptr);
     }
 #endif
     QWidget::focusOutEvent(e);
@@ -2190,7 +2190,7 @@ QMenu *QLineEdit::createStandardContextMenu()
     Q_D(QLineEdit);
     QMenu *popup = new QMenu(this);
     popup->setObjectName(QLatin1String("qt_edit_menu"));
-    QAction *action = 0;
+    QAction *action = nullptr;
 
     if (!isReadOnly()) {
         action = popup->addAction(QLineEdit::tr("&Undo") + ACCEL_KEY(QKeySequence::Undo));
diff --git a/src/widgets/widgets/qlineedit_p.cpp b/src/widgets/widgets/qlineedit_p.cpp
index d2b5f87906..feb34ef403 100644
--- a/src/widgets/widgets/qlineedit_p.cpp
+++ b/src/widgets/widgets/qlineedit_p.cpp
@@ -487,7 +487,7 @@ QLineEditPrivate::SideWidgetParameters QLineEditPrivate::sideWidgetParameters()
 {
     Q_Q(const QLineEdit);
     SideWidgetParameters result;
-    result.iconSize = q->style()->pixelMetric(QStyle::PM_SmallIconSize, 0, q);
+    result.iconSize = q->style()->pixelMetric(QStyle::PM_SmallIconSize, nullptr, q);
     result.margin = result.iconSize / 4;
     result.widgetWidth = result.iconSize + 6;
     result.widgetHeight = result.iconSize + 2;
@@ -566,12 +566,12 @@ QWidget *QLineEditPrivate::addAction(QAction *newAction, QAction *before, QLineE
 {
     Q_Q(QLineEdit);
     if (!newAction)
-        return 0;
+        return nullptr;
     if (!hasSideWidgets()) { // initial setup.
         QObject::connect(q, SIGNAL(textChanged(QString)), q, SLOT(_q_textChanged(QString)));
         lastTextSize = q->text().size();
     }
-    QWidget *w = 0;
+    QWidget *w = nullptr;
     // Store flags about QWidgetAction here since removeAction() may be called from ~QAction,
     // in which a qobject_cast<> no longer works.
 #if QT_CONFIG(action)
diff --git a/src/widgets/widgets/qlineedit_p.h b/src/widgets/widgets/qlineedit_p.h
index a11fea6bbe..5ae402b992 100644
--- a/src/widgets/widgets/qlineedit_p.h
+++ b/src/widgets/widgets/qlineedit_p.h
@@ -151,7 +151,7 @@ public:
     };
 
     QLineEditPrivate()
-        : control(0), frame(1), contextMenuEnabled(1), cursorVisible(0),
+        : control(nullptr), frame(1), contextMenuEnabled(1), cursorVisible(0),
         dragEnabled(0), clickCausedFocus(0), edited(0), hscroll(0), vscroll(0),
         alignment(Qt::AlignLeading | Qt::AlignVCenter),
         textMargins{0, 0, 0, 0},
diff --git a/src/widgets/widgets/qmainwindow.cpp b/src/widgets/widgets/qmainwindow.cpp
index 16ed699137..7f0f3342b6 100644
--- a/src/widgets/widgets/qmainwindow.cpp
+++ b/src/widgets/widgets/qmainwindow.cpp
@@ -78,7 +78,7 @@ class QMainWindowPrivate : public QWidgetPrivate
     Q_DECLARE_PUBLIC(QMainWindow)
 public:
     inline QMainWindowPrivate()
-        : layout(0), explicitIconSize(false), toolButtonStyle(Qt::ToolButtonIconOnly)
+        : layout(nullptr), explicitIconSize(false), toolButtonStyle(Qt::ToolButtonIconOnly)
 #ifdef Q_OS_OSX
             , useUnifiedToolBar(false)
 #endif
@@ -94,7 +94,7 @@ public:
 
     static inline QMainWindowLayout *mainWindowLayout(const QMainWindow *mainWindow)
     {
-        return mainWindow ? mainWindow->d_func()->layout : static_cast<QMainWindowLayout *>(0);
+        return mainWindow ? mainWindow->d_func()->layout : static_cast<QMainWindowLayout *>(nullptr);
     }
 };
 
@@ -152,10 +152,10 @@ void QMainWindowPrivate::init()
 
     topLayout->addItem(layout, 1, 1);
 #else
-    layout = new QMainWindowLayout(q, 0);
+    layout = new QMainWindowLayout(q, nullptr);
 #endif
 
-    const int metric = q->style()->pixelMetric(QStyle::PM_ToolBarIconSize, 0, q);
+    const int metric = q->style()->pixelMetric(QStyle::PM_ToolBarIconSize, nullptr, q);
     iconSize = QSize(metric, metric);
     q->setAttribute(Qt::WA_Hover);
 }
@@ -452,7 +452,7 @@ void QMainWindow::setIconSize(const QSize &iconSize)
     Q_D(QMainWindow);
     QSize sz = iconSize;
     if (!sz.isValid()) {
-        const int metric = style()->pixelMetric(QStyle::PM_ToolBarIconSize, 0, this);
+        const int metric = style()->pixelMetric(QStyle::PM_ToolBarIconSize, nullptr, this);
         sz = QSize(metric, metric);
     }
     if (d->iconSize != sz) {
@@ -652,8 +652,8 @@ QWidget *QMainWindow::takeCentralWidget()
     Q_D(QMainWindow);
     QWidget *oldcentralwidget = d->layout->centralWidget();
     if (oldcentralwidget) {
-        oldcentralwidget->setParent(0);
-        d->layout->setCentralWidget(0);
+        oldcentralwidget->setParent(nullptr);
+        d->layout->setCentralWidget(nullptr);
     }
     return oldcentralwidget;
 }
@@ -1478,7 +1478,7 @@ void QMainWindow::contextMenuEvent(QContextMenuEvent *event)
 QMenu *QMainWindow::createPopupMenu()
 {
     Q_D(QMainWindow);
-    QMenu *menu = 0;
+    QMenu *menu = nullptr;
 #if QT_CONFIG(dockwidget)
     QList<QDockWidget *> dockwidgets = findChildren<QDockWidget *>();
     if (dockwidgets.size()) {
diff --git a/src/widgets/widgets/qmainwindowlayout.cpp b/src/widgets/widgets/qmainwindowlayout.cpp
index 0fb3a86cf8..30562d8270 100644
--- a/src/widgets/widgets/qmainwindowlayout.cpp
+++ b/src/widgets/widgets/qmainwindowlayout.cpp
@@ -101,14 +101,14 @@ static void dumpLayout(QTextStream &qout, const QDockAreaLayoutItem &item, QStri
             << " gap:" << (item.flags & QDockAreaLayoutItem::GapItem)
             << " keepSize:" << (item.flags & QDockAreaLayoutItem::KeepSize) << '\n';
     indent += QLatin1String("  ");
-    if (item.widgetItem != 0) {
+    if (item.widgetItem != nullptr) {
         qout << indent << "widget: "
             << item.widgetItem->widget()->metaObject()->className()
             << " \"" << item.widgetItem->widget()->windowTitle() << "\"\n";
-    } else if (item.subinfo != 0) {
+    } else if (item.subinfo != nullptr) {
         qout << indent << "subinfo:\n";
         dumpLayout(qout, *item.subinfo, indent + QLatin1String("  "));
-    } else if (item.placeHolderItem != 0) {
+    } else if (item.placeHolderItem != nullptr) {
         QRect r = item.placeHolderItem->topLevelRect;
         qout << indent << "placeHolder: "
             << "pos: " << item.pos << " size:" << item.size
@@ -272,7 +272,7 @@ public:
     int frameWidth() const
     {
         return nativeWindowDeco() ? 0 :
-            parentWidget()->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, 0, parentWidget());
+            parentWidget()->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, nullptr, parentWidget());
     }
 
     QDockWidgetGroupWindow *groupWindow() const
@@ -727,7 +727,7 @@ void QMainWindowLayoutState::deleteCentralWidgetItem()
 {
 #if QT_CONFIG(dockwidget)
     delete dockAreaLayout.centralWidgetItem;
-    dockAreaLayout.centralWidgetItem = 0;
+    dockAreaLayout.centralWidgetItem = nullptr;
 #else
     delete centralWidgetItem;
     centralWidgetItem = 0;
@@ -749,7 +749,7 @@ QLayoutItem *QMainWindowLayoutState::itemAt(int index, int *x) const
         return centralWidgetItem;
 #endif
 
-    return 0;
+    return nullptr;
 }
 
 QLayoutItem *QMainWindowLayoutState::takeAt(int index, int *x)
@@ -770,7 +770,7 @@ QLayoutItem *QMainWindowLayoutState::takeAt(int index, int *x)
     }
 #endif
 
-    return 0;
+    return nullptr;
 }
 
 QList<int> QMainWindowLayoutState::indexOf(QWidget *widget) const
@@ -803,7 +803,7 @@ QList<int> QMainWindowLayoutState::indexOf(QWidget *widget) const
 bool QMainWindowLayoutState::contains(QWidget *widget) const
 {
 #if QT_CONFIG(dockwidget)
-    if (dockAreaLayout.centralWidgetItem != 0 && dockAreaLayout.centralWidgetItem->widget() == widget)
+    if (dockAreaLayout.centralWidgetItem != nullptr && dockAreaLayout.centralWidgetItem->widget() == widget)
         return true;
     if (!dockAreaLayout.indexOf(widget).isEmpty())
         return true;
@@ -821,11 +821,11 @@ bool QMainWindowLayoutState::contains(QWidget *widget) const
 
 void QMainWindowLayoutState::setCentralWidget(QWidget *widget)
 {
-    QLayoutItem *item = 0;
+    QLayoutItem *item = nullptr;
     //make sure we remove the widget
     deleteCentralWidgetItem();
 
-    if (widget != 0)
+    if (widget != nullptr)
         item = new QWidgetItemV2(widget);
 
 #if QT_CONFIG(dockwidget)
@@ -837,7 +837,7 @@ void QMainWindowLayoutState::setCentralWidget(QWidget *widget)
 
 QWidget *QMainWindowLayoutState::centralWidget() const
 {
-    QLayoutItem *item = 0;
+    QLayoutItem *item = nullptr;
 
 #if QT_CONFIG(dockwidget)
     item = dockAreaLayout.centralWidgetItem;
@@ -845,9 +845,9 @@ QWidget *QMainWindowLayoutState::centralWidget() const
     item = centralWidgetItem;
 #endif
 
-    if (item != 0)
+    if (item != nullptr)
         return item->widget();
-    return 0;
+    return nullptr;
 }
 
 QList<int> QMainWindowLayoutState::gapIndex(QWidget *widget,
@@ -978,7 +978,7 @@ QLayoutItem *QMainWindowLayoutState::item(const QList<int> &path)
         return dockAreaLayout.item(path.mid(1)).widgetItem;
 #endif // QT_CONFIG(dockwidget)
 
-    return 0;
+    return nullptr;
 }
 
 QRect QMainWindowLayoutState::itemRect(const QList<int> &path) const
@@ -1029,7 +1029,7 @@ QLayoutItem *QMainWindowLayoutState::plug(const QList<int> &path)
         return dockAreaLayout.plug(path.mid(1));
 #endif // QT_CONFIG(dockwidget)
 
-    return 0;
+    return nullptr;
 }
 
 QLayoutItem *QMainWindowLayoutState::unplug(const QList<int> &path, QMainWindowLayoutState *other)
@@ -1040,7 +1040,7 @@ QLayoutItem *QMainWindowLayoutState::unplug(const QList<int> &path, QMainWindowL
     Q_UNUSED(other);
 #else
     if (i == 0)
-        return toolBarAreaLayout.unplug(path.mid(1), other ? &other->toolBarAreaLayout : 0);
+        return toolBarAreaLayout.unplug(path.mid(1), other ? &other->toolBarAreaLayout : nullptr);
 #endif
 
 #if QT_CONFIG(dockwidget)
@@ -1048,7 +1048,7 @@ QLayoutItem *QMainWindowLayoutState::unplug(const QList<int> &path, QMainWindowL
         return dockAreaLayout.unplug(path.mid(1));
 #endif // QT_CONFIG(dockwidget)
 
-    return 0;
+    return nullptr;
 }
 
 void QMainWindowLayoutState::saveState(QDataStream &stream) const
@@ -1198,7 +1198,7 @@ bool QMainWindowLayoutState::restoreState(QDataStream &_stream,
                                 continue;
                             }
                             QDockAreaLayoutInfo *info = dockAreaLayout.info(oldPath);
-                            if (info == 0) {
+                            if (info == nullptr) {
                                 continue;
                             }
                             info->item_list.append(QDockAreaLayoutItem(new QDockWidgetItem(w)));
@@ -1249,7 +1249,7 @@ bool QMainWindowLayoutState::restoreState(QDataStream &_stream,
                             if (oldPath.isEmpty()) {
                                 continue;
                             }
-                            toolBarAreaLayout.docks[oldPath.at(0)].insertToolBar(0, w);
+                            toolBarAreaLayout.docks[oldPath.at(0)].insertToolBar(nullptr, w);
                         }
                     }
                 }
@@ -1755,7 +1755,7 @@ void QMainWindowTabBar::mouseReleaseEvent(QMouseEvent *e)
         if (dockPriv->state && dockPriv->state->dragging) {
             dockPriv->endDrag();
         }
-        draggingDock = 0;
+        draggingDock = nullptr;
     }
     QTabBar::mouseReleaseEvent(e);
 }
@@ -1780,7 +1780,7 @@ bool QMainWindowTabBar::event(QEvent *e)
 
 QTabBar *QMainWindowLayout::getTabBar()
 {
-    QTabBar *result = 0;
+    QTabBar *result = nullptr;
     if (!unusedTabBars.isEmpty()) {
         result = unusedTabBars.takeLast();
     } else {
@@ -1800,7 +1800,7 @@ QTabBar *QMainWindowLayout::getTabBar()
 // Allocates a new separator widget if needed
 QWidget *QMainWindowLayout::getSeparatorWidget()
 {
-    QWidget *result = 0;
+    QWidget *result = nullptr;
     if (!unusedSeparatorWidgets.isEmpty()) {
         result = unusedSeparatorWidgets.takeLast();
     } else {
@@ -1829,16 +1829,16 @@ QDockAreaLayoutInfo *QMainWindowLayout::dockInfo(QWidget *widget)
         if (info)
             return info;
     }
-    return 0;
+    return nullptr;
 }
 
 void QMainWindowLayout::tabChanged()
 {
     QTabBar *tb = qobject_cast<QTabBar*>(sender());
-    if (tb == 0)
+    if (tb == nullptr)
         return;
     QDockAreaLayoutInfo *info = dockInfo(tb);
-    if (info == 0)
+    if (info == nullptr)
         return;
 
     QDockWidget *activated = info->apply(false);
@@ -1866,7 +1866,7 @@ void QMainWindowLayout::tabMoved(int from, int to)
 void QMainWindowLayout::raise(QDockWidget *widget)
 {
     QDockAreaLayoutInfo *info = dockInfo(widget);
-    if (info == 0)
+    if (info == nullptr)
         return;
     if (!info->tabbed)
         return;
@@ -1897,7 +1897,7 @@ QLayoutItem *QMainWindowLayout::itemAt(int index) const
     if (statusbar && x++ == index)
         return statusbar;
 
-    return 0;
+    return nullptr;
 }
 
 QLayoutItem *QMainWindowLayout::takeAt(int index)
@@ -1909,7 +1909,7 @@ QLayoutItem *QMainWindowLayout::takeAt(int index)
         if (QWidget *w = ret->widget()) {
             widgetAnimator.abort(w);
             if (w == pluggingWidget)
-                pluggingWidget = 0;
+                pluggingWidget = nullptr;
         }
 
         if (savedState.isValid() ) {
@@ -1934,11 +1934,11 @@ QLayoutItem *QMainWindowLayout::takeAt(int index)
 
     if (statusbar && x++ == index) {
         QLayoutItem *ret = statusbar;
-        statusbar = 0;
+        statusbar = nullptr;
         return ret;
     }
 
-    return 0;
+    return nullptr;
 }
 
 void QMainWindowLayout::setGeometry(const QRect &_r)
@@ -2033,7 +2033,7 @@ static void fixToolBarOrientation(QLayoutItem *item, int dockPos)
 {
 #if QT_CONFIG(toolbar)
     QToolBar *toolBar = qobject_cast<QToolBar*>(item->widget());
-    if (toolBar == 0)
+    if (toolBar == nullptr)
         return;
 
     QRect oldGeo = toolBar->geometry();
@@ -2146,7 +2146,7 @@ bool QMainWindowLayout::plug(QLayoutItem *widgetItem)
         if (layout->nativeWindowDeco()) {
             globalRect.adjust(0, layout->titleHeight(), 0, 0);
         } else {
-            int fw = widget->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, 0, widget);
+            int fw = widget->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, nullptr, widget);
             globalRect.adjust(-fw, -fw, fw, fw);
         }
     }
@@ -2214,7 +2214,7 @@ void QMainWindowLayout::animationFinished(QWidget *widget)
                 QDockAreaLayoutItem &item = dstParentInfo->item_list[idx];
                 Q_ASSERT(item.widgetItem->widget() == dwgw);
                 delete item.widgetItem;
-                item.widgetItem = 0;
+                item.widgetItem = nullptr;
                 item.subinfo = new QDockAreaLayoutInfo(std::move(*srcInfo));
                 *srcInfo = QDockAreaLayoutInfo();
                 item.subinfo->reparentWidgets(currentHoveredFloat ? currentHoveredFloat.data()
@@ -2238,7 +2238,7 @@ void QMainWindowLayout::animationFinished(QWidget *widget)
 
         savedState.clear();
         currentGapPos.clear();
-        pluggingWidget = 0;
+        pluggingWidget = nullptr;
 #if QT_CONFIG(dockwidget)
         setCurrentHoveredFloat(nullptr);
 #endif
@@ -2283,16 +2283,16 @@ void QMainWindowLayout::restore(bool keepSavedState)
     if (!keepSavedState)
         savedState.clear();
     currentGapPos.clear();
-    pluggingWidget = 0;
+    pluggingWidget = nullptr;
     updateGapIndicator();
 }
 
 QMainWindowLayout::QMainWindowLayout(QMainWindow *mainwindow, QLayout *parentLayout)
-    : QLayout(parentLayout ? static_cast<QWidget *>(0) : mainwindow)
+    : QLayout(parentLayout ? static_cast<QWidget *>(nullptr) : mainwindow)
     , layoutState(mainwindow)
     , savedState(mainwindow)
     , dockOptions(QMainWindow::AnimatedDocks | QMainWindow::AllowTabbedDocks)
-    , statusbar(0)
+    , statusbar(nullptr)
 #if QT_CONFIG(dockwidget)
 #if QT_CONFIG(tabbar)
     , _documentMode(false)
@@ -2303,14 +2303,14 @@ QMainWindowLayout::QMainWindowLayout(QMainWindow *mainwindow, QLayout *parentLay
 #endif
 #endif // QT_CONFIG(dockwidget)
     , widgetAnimator(this)
-    , pluggingWidget(0)
+    , pluggingWidget(nullptr)
 {
     if (parentLayout)
         setParent(parentLayout);
 
 #if QT_CONFIG(dockwidget)
 #if QT_CONFIG(tabbar)
-    sep = mainwindow->style()->pixelMetric(QStyle::PM_DockWidgetSeparatorExtent, 0, mainwindow);
+    sep = mainwindow->style()->pixelMetric(QStyle::PM_DockWidgetSeparatorExtent, nullptr, mainwindow);
 #endif
 
 #if QT_CONFIG(tabwidget)
@@ -2318,7 +2318,7 @@ QMainWindowLayout::QMainWindowLayout(QMainWindow *mainwindow, QLayout *parentLay
         tabPositions[i] = QTabWidget::South;
 #endif
 #endif // QT_CONFIG(dockwidget)
-    pluggingWidget = 0;
+    pluggingWidget = nullptr;
 
     setObjectName(mainwindow->objectName() + QLatin1String("_layout"));
 }
@@ -2354,7 +2354,7 @@ void QMainWindowLayout::setStatusBar(QStatusBar *sb)
     if (sb)
         addChildWidget(sb);
     delete statusbar;
-    statusbar = sb ? new QWidgetItemV2(sb) : 0;
+    statusbar = sb ? new QWidgetItemV2(sb) : nullptr;
     invalidate();
 }
 #endif // QT_CONFIG(statusbar)
@@ -2366,7 +2366,7 @@ QWidget *QMainWindowLayout::centralWidget() const
 
 void QMainWindowLayout::setCentralWidget(QWidget *widget)
 {
-    if (widget != 0)
+    if (widget != nullptr)
         addChildWidget(widget);
     layoutState.setCentralWidget(widget);
     if (savedState.isValid()) {
@@ -2453,7 +2453,7 @@ QLayoutItem *QMainWindowLayout::unplug(QWidget *widget, bool group)
 #endif
     QList<int> path = layoutState.indexOf(widget);
     if (path.isEmpty())
-        return 0;
+        return nullptr;
 
     QLayoutItem *item = layoutState.item(path);
     if (widget->isWindow())
@@ -2561,7 +2561,7 @@ static QTabBar::Shape tabwidgetPositionToTabBarShape(QWidget *w)
 void QMainWindowLayout::hover(QLayoutItem *widgetItem, const QPoint &mousePos)
 {
     if (!parentWidget()->isVisible() || parentWidget()->isMinimized()
-        || pluggingWidget != 0 || widgetItem == 0)
+        || pluggingWidget != nullptr || widgetItem == nullptr)
         return;
 
     QWidget *widget = widgetItem->widget();
diff --git a/src/widgets/widgets/qmdiarea.cpp b/src/widgets/widgets/qmdiarea.cpp
index 6e3de1b1ff..3272ac440b 100644
--- a/src/widgets/widgets/qmdiarea.cpp
+++ b/src/widgets/widgets/qmdiarea.cpp
@@ -245,7 +245,7 @@ static inline bool useScrollBar(const QRect &childrenRect, const QSize &maxViewp
 static inline QMdiArea *mdiAreaParent(QWidget *widget)
 {
     if (!widget)
-        return 0;
+        return nullptr;
 
     QWidget *parent = widget->parentWidget();
     while (parent) {
@@ -253,7 +253,7 @@ static inline QMdiArea *mdiAreaParent(QWidget *widget)
             return area;
         parent = parent->parentWidget();
     }
-    return 0;
+    return nullptr;
 }
 
 #if QT_CONFIG(tabwidget)
@@ -352,7 +352,7 @@ void SimpleCascader::rearrange(QList<QWidget *> &widgets, const QRect &domain) c
     int titleBarHeight = widgets.at(0)->style()->pixelMetric(QStyle::PM_TitleBarHeight, &options, widgets.at(0));
     const QFontMetrics fontMetrics = QFontMetrics(QApplication::font("QMdiSubWindowTitleBar"));
     const int dy = qMax(titleBarHeight - (titleBarHeight - fontMetrics.height()) / 2, 1)
-        + widgets.at(0)->style()->pixelMetric(QStyle::PM_FocusFrameVMargin, 0, widgets.at(0));
+        + widgets.at(0)->style()->pixelMetric(QStyle::PM_FocusFrameVMargin, nullptr, widgets.at(0));
 
     const int n = widgets.size();
     const int nrows = qMax((domain.height() - (topOffset + bottomOffset)) / dy, 1);
@@ -648,7 +648,7 @@ void QMdiAreaTabBar::contextMenuEvent(QContextMenuEvent *event)
 QMdiSubWindow *QMdiAreaTabBar::subWindowFromIndex(int index) const
 {
     if (index < 0 || index >= count())
-        return 0;
+        return nullptr;
 
     QMdiArea *mdiArea = qobject_cast<QMdiArea *>(parentWidget());
     Q_ASSERT(mdiArea);
@@ -667,15 +667,15 @@ QMdiSubWindow *QMdiAreaTabBar::subWindowFromIndex(int index) const
     \internal
 */
 QMdiAreaPrivate::QMdiAreaPrivate()
-    : cascader(0),
-      regularTiler(0),
-      iconTiler(0),
-      placer(0),
+    : cascader(nullptr),
+      regularTiler(nullptr),
+      iconTiler(nullptr),
+      placer(nullptr),
 #if QT_CONFIG(rubberband)
-      rubberBand(0),
+      rubberBand(nullptr),
 #endif
 #if QT_CONFIG(tabbar)
-      tabBar(0),
+      tabBar(nullptr),
 #endif
       activationOrder(QMdiArea::CreationOrder),
       viewMode(QMdiArea::SubWindowView),
@@ -1070,7 +1070,7 @@ void QMdiAreaPrivate::emitWindowActivated(QMdiSubWindow *activeWindow)
 
     Q_ASSERT(aboutToBecomeActive == activeWindow);
     active = activeWindow;
-    aboutToBecomeActive = 0;
+    aboutToBecomeActive = nullptr;
     Q_ASSERT(active->d_func()->isActive);
 
 #if QT_CONFIG(tabbar)
@@ -1093,20 +1093,20 @@ void QMdiAreaPrivate::resetActiveWindow(QMdiSubWindow *deactivatedWindow)
     if (deactivatedWindow) {
         if (deactivatedWindow != active)
             return;
-        active = 0;
+        active = nullptr;
         if ((aboutToBecomeActive || isActivated || lastWindowAboutToBeDestroyed())
             && !isExplicitlyDeactivated(deactivatedWindow) && !q->window()->isMinimized()) {
             return;
         }
-        emit q->subWindowActivated(0);
+        emit q->subWindowActivated(nullptr);
         return;
     }
 
     if (aboutToBecomeActive)
         return;
 
-    active = 0;
-    emit q->subWindowActivated(0);
+    active = nullptr;
+    emit q->subWindowActivated(nullptr);
 }
 
 /*!
@@ -1171,7 +1171,7 @@ void QMdiAreaPrivate::updateScrollBars()
     QSize hbarExtent = hbar->sizeHint();
     QSize vbarExtent = vbar->sizeHint();
 
-    if (q->style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, 0, q)) {
+    if (q->style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, nullptr, q)) {
         const int doubleFrameWidth = frameWidth * 2;
         if (hbarpolicy == Qt::ScrollBarAlwaysOn)
             maxSize.rheight() -= doubleFrameWidth;
@@ -1232,7 +1232,7 @@ void QMdiAreaPrivate::internalRaise(QMdiSubWindow *mdiChild) const
     if (!sanityCheck(mdiChild, "QMdiArea::internalRaise") || childWindows.size() < 2)
         return;
 
-    QMdiSubWindow *stackUnderChild = 0;
+    QMdiSubWindow *stackUnderChild = nullptr;
     if (!windowStaysOnTop(mdiChild)) {
         const auto children = viewport->children(); // take a copy, as raising/stacking under changes the order
         for (QObject *object : children) {
@@ -1282,8 +1282,8 @@ QRect QMdiAreaPrivate::resizeToMinimumTileSize(const QSize &minSubWindowSize, in
             minAreaHeight += hbar->height();
         if (vbar->isVisible())
             minAreaWidth += vbar->width();
-        if (q->style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, 0, q)) {
-            const int frame = q->style()->pixelMetric(QStyle::PM_DefaultFrameWidth, 0, q);
+        if (q->style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, nullptr, q)) {
+            const int frame = q->style()->pixelMetric(QStyle::PM_DefaultFrameWidth, nullptr, q);
             minAreaWidth += 2 * frame;
             minAreaHeight += 2 * frame;
         }
@@ -1427,7 +1427,7 @@ void QMdiAreaPrivate::disconnectSubWindow(QObject *subWindow)
         return;
 
     Q_Q(QMdiArea);
-    QObject::disconnect(subWindow, 0, q, 0);
+    QObject::disconnect(subWindow, nullptr, q, nullptr);
     subWindow->removeEventFilter(q);
 }
 
@@ -1438,11 +1438,11 @@ QMdiSubWindow *QMdiAreaPrivate::nextVisibleSubWindow(int increaseFactor, QMdiAre
                                                      int removedIndex, int fromIndex) const
 {
     if (childWindows.isEmpty())
-        return 0;
+        return nullptr;
 
     Q_Q(const QMdiArea);
     const QList<QMdiSubWindow *> subWindows = q->subWindowList(order);
-    QMdiSubWindow *current = 0;
+    QMdiSubWindow *current = nullptr;
 
     if (removedIndex < 0) {
         if (fromIndex >= 0 && fromIndex < subWindows.size())
@@ -1482,7 +1482,7 @@ QMdiSubWindow *QMdiAreaPrivate::nextVisibleSubWindow(int increaseFactor, QMdiAre
 
     if (!subWindows.at(index)->isHidden())
         return subWindows.at(index);
-    return 0;
+    return nullptr;
 }
 
 /*!
@@ -1603,7 +1603,7 @@ void QMdiAreaPrivate::setViewMode(QMdiArea::ViewMode mode)
     { // SubWindowView
 #if QT_CONFIG(tabbar)
         delete tabBar;
-        tabBar = 0;
+        tabBar = nullptr;
 #endif // QT_CONFIG(tabbar)
 
         viewMode = mode;
@@ -1704,7 +1704,7 @@ QMdiArea::QMdiArea(QWidget *parent)
     setFrameStyle(QFrame::NoFrame);
     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
-    setViewport(0);
+    setViewport(nullptr);
     setFocusPolicy(Qt::NoFocus);
     QApplication::instance()->installEventFilter(this);
 }
@@ -1716,16 +1716,16 @@ QMdiArea::~QMdiArea()
 {
     Q_D(QMdiArea);
     delete d->cascader;
-    d->cascader = 0;
+    d->cascader = nullptr;
 
     delete d->regularTiler;
-    d->regularTiler = 0;
+    d->regularTiler = nullptr;
 
     delete d->iconTiler;
-    d->iconTiler = 0;
+    d->iconTiler = nullptr;
 
     delete d->placer;
-    d->placer = 0;
+    d->placer = nullptr;
 }
 
 /*!
@@ -1760,8 +1760,8 @@ QSize QMdiArea::sizeHint() const
 QSize QMdiArea::minimumSizeHint() const
 {
     Q_D(const QMdiArea);
-    QSize size(style()->pixelMetric(QStyle::PM_MdiSubWindowMinimizedWidth, 0, this),
-               style()->pixelMetric(QStyle::PM_TitleBarHeight, 0, this));
+    QSize size(style()->pixelMetric(QStyle::PM_MdiSubWindowMinimizedWidth, nullptr, this),
+               style()->pixelMetric(QStyle::PM_TitleBarHeight, nullptr, this));
     size = size.expandedTo(QAbstractScrollArea::minimumSizeHint());
     if (!d->scrollBarsEnabled()) {
         for (QMdiSubWindow *child : d->childWindows) {
@@ -1965,7 +1965,7 @@ QMdiSubWindow *QMdiArea::addSubWindow(QWidget *widget, Qt::WindowFlags windowFla
 {
     if (Q_UNLIKELY(!widget)) {
         qWarning("QMdiArea::addSubWindow: null pointer to widget");
-        return 0;
+        return nullptr;
     }
 
     Q_D(QMdiArea);
@@ -2027,7 +2027,7 @@ void QMdiArea::removeSubWindow(QWidget *widget)
         d->childWindows.removeAll(child);
         d->indicesToActivatedChildren.removeAll(index);
         d->updateActiveWindow(index, d->active == child);
-        child->setParent(0);
+        child->setParent(nullptr);
         return;
     }
 
@@ -2036,7 +2036,7 @@ void QMdiArea::removeSubWindow(QWidget *widget)
         if (!sanityCheck(child, "QMdiArea::removeSubWindow"))
             continue;
         if (child->widget() == widget) {
-            child->setWidget(0);
+            child->setWidget(nullptr);
             Q_ASSERT(!child->widget());
             found = true;
             break;
diff --git a/src/widgets/widgets/qmdisubwindow.cpp b/src/widgets/widgets/qmdisubwindow.cpp
index a0286dfcb1..84568c35db 100644
--- a/src/widgets/widgets/qmdisubwindow.cpp
+++ b/src/widgets/widgets/qmdisubwindow.cpp
@@ -253,7 +253,7 @@ static inline ControlElement<T> *ptr(QWidget *widget)
             && strcmp(widget->metaObject()->className(), T::staticMetaObject.className()) == 0) {
         return static_cast<ControlElement<T> *>(widget);
     }
-    return 0;
+    return nullptr;
 }
 
 QString QMdiSubWindowPrivate::originalWindowTitle()
@@ -364,7 +364,7 @@ class ControlLabel : public QWidget
 {
     Q_OBJECT
 public:
-    ControlLabel(QMdiSubWindow *subWindow, QWidget *parent = 0);
+    ControlLabel(QMdiSubWindow *subWindow, QWidget *parent = nullptr);
 
     QSize sizeHint() const override;
 
@@ -481,8 +481,8 @@ void ControlLabel::updateWindowIcon()
 {
     QIcon menuIcon = windowIcon();
     if (menuIcon.isNull())
-        menuIcon = style()->standardIcon(QStyle::SP_TitleBarMenuButton, 0, parentWidget());
-    const int iconSize = style()->pixelMetric(QStyle::PM_TitleBarButtonIconSize, 0, parentWidget());
+        menuIcon = style()->standardIcon(QStyle::SP_TitleBarMenuButton, nullptr, parentWidget());
+    const int iconSize = style()->pixelMetric(QStyle::PM_TitleBarButtonIconSize, nullptr, parentWidget());
     label = menuIcon.pixmap(iconSize);
     update();
 }
@@ -496,7 +496,7 @@ class ControllerWidget : public QWidget
 {
     Q_OBJECT
 public:
-    ControllerWidget(QMdiSubWindow *subWindow, QWidget *parent = 0);
+    ControllerWidget(QMdiSubWindow *subWindow, QWidget *parent = nullptr);
     QSize sizeHint() const override;
     void setControlVisible(QMdiSubWindowPrivate::WindowStateAction action, bool visible);
     inline bool hasVisibleControls() const
@@ -542,7 +542,7 @@ ControllerWidget::ControllerWidget(QMdiSubWindow *subWindow, QWidget *parent)
       activeControl(QStyle::SC_None),
       hoverControl(QStyle::SC_None),
       visibleControls(QStyle::SC_None),
-      mdiArea(0)
+      mdiArea(nullptr)
 {
     if (subWindow->parentWidget())
         mdiArea = qobject_cast<QMdiArea *>(subWindow->parentWidget()->parentWidget());
@@ -697,10 +697,10 @@ void ControllerWidget::initStyleOption(QStyleOptionComplex *option) const
 */
 ControlContainer::ControlContainer(QMdiSubWindow *mdiChild)
     : QObject(mdiChild),
-      previousLeft(0),
-      previousRight(0),
+      previousLeft(nullptr),
+      previousRight(nullptr),
 #if QT_CONFIG(menubar)
-      m_menuBar(0),
+      m_menuBar(nullptr),
 #endif
       mdiChild(mdiChild)
 {
@@ -725,9 +725,9 @@ ControlContainer::~ControlContainer()
     removeButtonsFromMenuBar();
 #endif
     delete m_menuLabel;
-    m_menuLabel = 0;
+    m_menuLabel = nullptr;
     delete m_controllerWidget;
-    m_controllerWidget = 0;
+    m_controllerWidget = nullptr;
 }
 
 #if QT_CONFIG(menubar)
@@ -741,12 +741,12 @@ QMenuBar *QMdiSubWindowPrivate::menuBar() const
 #else
     Q_Q(const QMdiSubWindow);
     if (!q->isMaximized() || drawTitleBarWhenMaximized() || isChildOfTabbedQMdiArea(q))
-        return 0;
+        return nullptr;
 
     if (QMainWindow *mainWindow = qobject_cast<QMainWindow *>(q->window()))
         return mainWindow->menuBar();
 
-    return 0;
+    return nullptr;
 #endif
 }
 
@@ -790,50 +790,50 @@ void ControlContainer::removeButtonsFromMenuBar(QMenuBar *menuBar)
 {
     if (menuBar && menuBar != m_menuBar) {
         // m_menubar was deleted while sub-window was maximized
-        previousRight = 0;
-        previousLeft = 0;
+        previousRight = nullptr;
+        previousLeft = nullptr;
         m_menuBar = menuBar;
     }
 
     if (!m_menuBar || !mdiChild || qt_widget_private(mdiChild->window())->data.in_destructor)
         return;
 
-    QMdiSubWindow *child = 0;
+    QMdiSubWindow *child = nullptr;
     if (m_controllerWidget) {
         QWidget *currentRight = m_menuBar->cornerWidget(Qt::TopRightCorner);
         if (currentRight == m_controllerWidget) {
             if (ControlElement<ControllerWidget> *ce = ptr<ControllerWidget>(previousRight)) {
                 if (!ce->mdiChild || !ce->mdiChild->isMaximized())
-                    previousRight = 0;
+                    previousRight = nullptr;
                 else
                     child = ce->mdiChild;
             }
             m_menuBar->setCornerWidget(previousRight, Qt::TopRightCorner);
             if (previousRight) {
                 previousRight->show();
-                previousRight = 0;
+                previousRight = nullptr;
             }
         }
         m_controllerWidget->hide();
-        m_controllerWidget->setParent(0);
+        m_controllerWidget->setParent(nullptr);
     }
     if (m_menuLabel) {
         QWidget *currentLeft = m_menuBar->cornerWidget(Qt::TopLeftCorner);
         if (currentLeft == m_menuLabel) {
             if (ControlElement<ControlLabel> *ce = ptr<ControlLabel>(previousLeft)) {
                 if (!ce->mdiChild || !ce->mdiChild->isMaximized())
-                    previousLeft = 0;
+                    previousLeft = nullptr;
                 else if (!child)
                     child = mdiChild;
             }
             m_menuBar->setCornerWidget(previousLeft, Qt::TopLeftCorner);
             if (previousLeft) {
                 previousLeft->show();
-                previousLeft = 0;
+                previousLeft = nullptr;
             }
         }
         m_menuLabel->hide();
-        m_menuLabel->setParent(0);
+        m_menuLabel->setParent(nullptr);
     }
     m_menuBar->update();
     if (child)
@@ -854,14 +854,14 @@ void ControlContainer::updateWindowIcon(const QIcon &windowIcon)
     \internal
 */
 QMdiSubWindowPrivate::QMdiSubWindowPrivate()
-    : baseWidget(0),
-      restoreFocusWidget(0),
-      controlContainer(0),
+    : baseWidget(nullptr),
+      restoreFocusWidget(nullptr),
+      controlContainer(nullptr),
 #if QT_CONFIG(sizegrip)
-      sizeGrip(0),
+      sizeGrip(nullptr),
 #endif
 #if QT_CONFIG(rubberband)
-      rubberBand(0),
+      rubberBand(nullptr),
 #endif
       userMinimumSize(0,0),
       resizeEnabled(true),
@@ -926,7 +926,7 @@ void QMdiSubWindowPrivate::_q_enterInteractiveMode()
         pressPos = QPoint(q->width() / 2, titleBarHeight() - 1);
     } else if (actions[ResizeAction] && actions[ResizeAction] == action) {
         currentOperation = q->isLeftToRight() ? BottomRightResize : BottomLeftResize;
-        int offset = q->style()->pixelMetric(QStyle::PM_MdiSubWindowFrameWidth, 0, q) / 2;
+        int offset = q->style()->pixelMetric(QStyle::PM_MdiSubWindowFrameWidth, nullptr, q) / 2;
         int x = q->isLeftToRight() ? q->width() - offset : offset;
         pressPos = QPoint(x, q->height() - offset);
     } else {
@@ -1009,8 +1009,8 @@ void QMdiSubWindowPrivate::removeBaseWidget()
     lastChildWindowTitle.clear();
     // QTBUG-47993: parent widget can be reset before this call
     if (baseWidget->parentWidget() == q)
-        baseWidget->setParent(0);
-    baseWidget = 0;
+        baseWidget->setParent(nullptr);
+    baseWidget = nullptr;
     isWidgetHiddenByUs = false;
 }
 
@@ -1047,19 +1047,19 @@ void QMdiSubWindowPrivate::createSystemMenu()
     systemMenu->installEventFilter(q);
     const QStyle *style = q->style();
     addToSystemMenu(RestoreAction, QMdiSubWindow::tr("&Restore"), SLOT(showNormal()));
-    actions[RestoreAction]->setIcon(style->standardIcon(QStyle::SP_TitleBarNormalButton, 0, q));
+    actions[RestoreAction]->setIcon(style->standardIcon(QStyle::SP_TitleBarNormalButton, nullptr, q));
     actions[RestoreAction]->setEnabled(false);
     addToSystemMenu(MoveAction, QMdiSubWindow::tr("&Move"), SLOT(_q_enterInteractiveMode()));
     addToSystemMenu(ResizeAction, QMdiSubWindow::tr("&Size"), SLOT(_q_enterInteractiveMode()));
     addToSystemMenu(MinimizeAction, QMdiSubWindow::tr("Mi&nimize"), SLOT(showMinimized()));
-    actions[MinimizeAction]->setIcon(style->standardIcon(QStyle::SP_TitleBarMinButton, 0, q));
+    actions[MinimizeAction]->setIcon(style->standardIcon(QStyle::SP_TitleBarMinButton, nullptr, q));
     addToSystemMenu(MaximizeAction, QMdiSubWindow::tr("Ma&ximize"), SLOT(showMaximized()));
-    actions[MaximizeAction]->setIcon(style->standardIcon(QStyle::SP_TitleBarMaxButton, 0, q));
+    actions[MaximizeAction]->setIcon(style->standardIcon(QStyle::SP_TitleBarMaxButton, nullptr, q));
     addToSystemMenu(StayOnTopAction, QMdiSubWindow::tr("Stay on &Top"), SLOT(_q_updateStaysOnTopHint()));
     actions[StayOnTopAction]->setCheckable(true);
     systemMenu->addSeparator();
     addToSystemMenu(CloseAction, QMdiSubWindow::tr("&Close"), SLOT(close()));
-    actions[CloseAction]->setIcon(style->standardIcon(QStyle::SP_TitleBarCloseButton, 0, q));
+    actions[CloseAction]->setIcon(style->standardIcon(QStyle::SP_TitleBarCloseButton, nullptr, q));
 #if !defined(QT_NO_SHORTCUT)
     actions[CloseAction]->setShortcuts(QKeySequence::Close);
 #endif
@@ -1461,7 +1461,7 @@ void QMdiSubWindowPrivate::setActive(bool activate, bool changeFocus)
         ensureWindowState(Qt::WindowActive);
     }
 
-    int frameWidth = q->style()->pixelMetric(QStyle::PM_MdiSubWindowFrameWidth, 0, q);
+    int frameWidth = q->style()->pixelMetric(QStyle::PM_MdiSubWindowFrameWidth, nullptr, q);
     int titleBarHeight = this->titleBarHeight();
     QRegion windowDecoration = QRegion(0, 0, q->width(), q->height());
     windowDecoration -= QRegion(frameWidth, titleBarHeight, q->width() - 2 * frameWidth,
@@ -1543,7 +1543,7 @@ QRegion QMdiSubWindowPrivate::getRegion(Operation operation) const
     int width = q->width();
     int height = q->height();
     int titleBarHeight = this->titleBarHeight();
-    int frameWidth = q->style()->pixelMetric(QStyle::PM_MdiSubWindowFrameWidth, 0, q);
+    int frameWidth = q->style()->pixelMetric(QStyle::PM_MdiSubWindowFrameWidth, nullptr, q);
     int cornerConst = titleBarHeight - frameWidth;
     int titleBarConst = 2 * titleBarHeight;
 
@@ -1738,7 +1738,7 @@ void QMdiSubWindowPrivate::sizeParameters(int *margin, int *minWidth) const
     if (q->isMaximized() && !drawTitleBarWhenMaximized())
         *margin = 0;
     else
-        *margin = q->style()->pixelMetric(QStyle::PM_MdiSubWindowFrameWidth, 0, q);
+        *margin = q->style()->pixelMetric(QStyle::PM_MdiSubWindowFrameWidth, nullptr, q);
 
     QStyleOptionTitleBar opt = this->titleBarOptions();
     int tempWidth = 0;
@@ -1767,7 +1767,7 @@ bool QMdiSubWindowPrivate::drawTitleBarWhenMaximized() const
     if (isChildOfTabbedQMdiArea(q))
         return false;
 
-    if (q->style()->styleHint(QStyle::SH_Workspace_FillSpaceOnMaximize, 0, q))
+    if (q->style()->styleHint(QStyle::SH_Workspace_FillSpaceOnMaximize, nullptr, q))
         return true;
 #if !QT_CONFIG(menubar) || !QT_CONFIG(mainwindow)
     Q_UNUSED(isChildOfQMdiSubWindow);
@@ -1833,7 +1833,7 @@ void QMdiSubWindowPrivate::removeButtonsFromMenuBar()
     if (!controlContainer || isChildOfTabbedQMdiArea(q))
         return;
 
-    QMenuBar *currentMenuBar = 0;
+    QMenuBar *currentMenuBar = nullptr;
 #if QT_CONFIG(mainwindow)
     if (QMainWindow *mainWindow = qobject_cast<QMainWindow *>(q->window())) {
         // NB! We can't use menuBar() here because that one will actually create
@@ -1863,7 +1863,7 @@ void QMdiSubWindowPrivate::updateWindowTitle(bool isRequestFromChild)
         return;
     }
 
-    QWidget *titleWidget = 0;
+    QWidget *titleWidget = nullptr;
     if (isRequestFromChild)
         titleWidget = baseWidget;
     else
@@ -2131,7 +2131,7 @@ QSize QMdiSubWindowPrivate::iconSize() const
     Q_Q(const QMdiSubWindow);
     if (!parent || q->windowFlags() & Qt::FramelessWindowHint)
         return QSize(-1, -1);
-    return QSize(q->style()->pixelMetric(QStyle::PM_MdiSubWindowMinimizedWidth, 0, q), titleBarHeight());
+    return QSize(q->style()->pixelMetric(QStyle::PM_MdiSubWindowMinimizedWidth, nullptr, q), titleBarHeight());
 }
 
 #if QT_CONFIG(sizegrip)
@@ -2233,7 +2233,7 @@ QMdiSubWindow::QMdiSubWindow(QWidget *parent, Qt::WindowFlags flags)
     // We don't want the menu icon by default on mac.
 #ifndef Q_OS_MAC
     if (windowIcon().isNull())
-        d->menuIcon = style()->standardIcon(QStyle::SP_TitleBarMenuButton, 0, this);
+        d->menuIcon = style()->standardIcon(QStyle::SP_TitleBarMenuButton, nullptr, this);
     else
         d->menuIcon = windowIcon();
 #endif
@@ -2340,7 +2340,7 @@ QWidget *QMdiSubWindow::maximizedButtonsWidget() const
         && !isChildOfTabbedQMdiArea(this)) {
         return d->controlContainer->controllerWidget();
     }
-    return 0;
+    return nullptr;
 }
 
 /*!
@@ -2353,7 +2353,7 @@ QWidget *QMdiSubWindow::maximizedSystemMenuIconWidget() const
         && !isChildOfTabbedQMdiArea(this)) {
         return d->controlContainer->systemMenuLabel();
     }
-    return 0;
+    return nullptr;
 }
 
 /*!
@@ -2476,7 +2476,7 @@ void QMdiSubWindow::setSystemMenu(QMenu *systemMenu)
 
     if (d->systemMenu) {
         delete d->systemMenu;
-        d->systemMenu = 0;
+        d->systemMenu = nullptr;
     }
 
     if (!systemMenu)
@@ -2860,7 +2860,7 @@ bool QMdiSubWindow::event(QEvent *event)
     case QEvent::WindowIconChange:
         d->menuIcon = windowIcon();
         if (d->menuIcon.isNull())
-            d->menuIcon = style()->standardIcon(QStyle::SP_TitleBarMenuButton, 0, this);
+            d->menuIcon = style()->standardIcon(QStyle::SP_TitleBarMenuButton, nullptr, this);
         if (d->controlContainer)
             d->controlContainer->updateWindowIcon(d->menuIcon);
         if (!maximizedSystemMenuIconWidget())
@@ -3135,7 +3135,7 @@ void QMdiSubWindow::paintEvent(QPaintEvent *paintEvent)
     if (isMinimized() && !d->hasBorder(d->cachedStyleOptions))
         return;
 
-    frameOptions.lineWidth = style()->pixelMetric(QStyle::PM_MdiSubWindowFrameWidth, 0, this);
+    frameOptions.lineWidth = style()->pixelMetric(QStyle::PM_MdiSubWindowFrameWidth, nullptr, this);
 
     // ### Ensure that we do not require setting the cliprect for 4.4
     if (!isMinimized() && !d->hasBorder(d->cachedStyleOptions))
@@ -3510,7 +3510,7 @@ QSize QMdiSubWindow::minimumSizeHint() const
     if (d->sizeGrip && d->sizeGrip->isVisibleTo(const_cast<QMdiSubWindow *>(this)))
         sizeGripHeight = d->sizeGrip->height();
     else if (parent() && isMacStyle(style()) && !d->sizeGrip)
-        sizeGripHeight = style()->pixelMetric(QStyle::PM_SizeGripSize, 0, this);
+        sizeGripHeight = style()->pixelMetric(QStyle::PM_SizeGripSize, nullptr, this);
     minHeight = qMax(minHeight, decorationHeight + sizeGripHeight);
 #endif
 
diff --git a/src/widgets/widgets/qmenu.cpp b/src/widgets/widgets/qmenu.cpp
index 51b458f03a..e7f80263c8 100644
--- a/src/widgets/widgets/qmenu.cpp
+++ b/src/widgets/widgets/qmenu.cpp
@@ -83,7 +83,7 @@
 
 QT_BEGIN_NAMESPACE
 
-QMenu *QMenuPrivate::mouseDown = 0;
+QMenu *QMenuPrivate::mouseDown = nullptr;
 
 /* QMenu code */
 // internal class used for the torn off popup
@@ -96,7 +96,7 @@ class QTornOffMenu : public QMenu
     public:
         QTornOffMenuPrivate(QMenu *p) : causedMenu(p), initialized(false) {
             tornoff = 1;
-            causedPopup.widget = 0;
+            causedPopup.widget = nullptr;
             causedPopup.action = p->d_func()->causedPopup.action;
             causedStack = p->d_func()->calcCausedStack();
         }
@@ -106,11 +106,11 @@ class QTornOffMenu : public QMenu
             QSize size = menuSize;
             const QPoint p = (!initialized) ? causedMenu->pos() : q->pos();
             QRect screen = popupGeometry(QDesktopWidgetPrivate::screenNumber(p));
-            const int desktopFrame = q->style()->pixelMetric(QStyle::PM_MenuDesktopFrameWidth, 0, q);
-            const int titleBarHeight = q->style()->pixelMetric(QStyle::PM_TitleBarHeight, 0, q);
+            const int desktopFrame = q->style()->pixelMetric(QStyle::PM_MenuDesktopFrameWidth, nullptr, q);
+            const int titleBarHeight = q->style()->pixelMetric(QStyle::PM_TitleBarHeight, nullptr, q);
             if (scroll && (size.height() > screen.height() - titleBarHeight || size.width() > screen.width())) {
-                const int fw = q->style()->pixelMetric(QStyle::PM_MenuPanelWidth, 0, q);
-                const int hmargin = q->style()->pixelMetric(QStyle::PM_MenuHMargin, 0, q);
+                const int fw = q->style()->pixelMetric(QStyle::PM_MenuPanelWidth, nullptr, q);
+                const int hmargin = q->style()->pixelMetric(QStyle::PM_MenuHMargin, nullptr, q);
                 scroll->scrollFlags |= uint(QMenuPrivate::QMenuScroller::ScrollDown);
                 size.setWidth(qMin(actionRects.at(getLastVisibleAction()).right() + fw + hmargin + rightmargin + 1, screen.width()));
                 size.setHeight(screen.height() - desktopFrame * 2 - titleBarHeight);
@@ -202,15 +202,15 @@ void QMenuPrivate::init()
         if (!tornPopup.isNull())
             tornPopup->updateWindowTitle();
     });
-    q->setMouseTracking(q->style()->styleHint(QStyle::SH_Menu_MouseTracking, 0, q));
-    if (q->style()->styleHint(QStyle::SH_Menu_Scrollable, 0, q)) {
+    q->setMouseTracking(q->style()->styleHint(QStyle::SH_Menu_MouseTracking, nullptr, q));
+    if (q->style()->styleHint(QStyle::SH_Menu_Scrollable, nullptr, q)) {
         scroll = new QMenuPrivate::QMenuScroller;
         scroll->scrollFlags = QMenuPrivate::QMenuScroller::ScrollNone;
     }
 
     sloppyState.initialize(q);
     delayState.initialize(q);
-    mousePopupDelay = q->style()->styleHint(QStyle::SH_Menu_SubMenuPopupDelay, 0, q);
+    mousePopupDelay = q->style()->styleHint(QStyle::SH_Menu_SubMenuPopupDelay, nullptr, q);
 }
 
 QPlatformMenu *QMenuPrivate::createPlatformMenu()
@@ -262,7 +262,7 @@ void QMenuPrivate::copyActionToPlatformItem(const QAction *action, QPlatformMenu
             item->setIconSize(w->style()->pixelMetric(QStyle::PM_SmallIconSize, &opt, w));
         } else {
             QStyleOption opt;
-            item->setIconSize(QApplication::style()->pixelMetric(QStyle::PM_SmallIconSize, &opt, 0));
+            item->setIconSize(QApplication::style()->pixelMetric(QStyle::PM_SmallIconSize, &opt, nullptr));
         }
     } else {
         item->setIcon(QIcon());
@@ -283,7 +283,7 @@ void QMenuPrivate::copyActionToPlatformItem(const QAction *action, QPlatformMenu
             action->menu()->setPlatformMenu(platformMenu->createSubMenu());
         item->setMenu(action->menu()->platformMenu());
     } else {
-        item->setMenu(0);
+        item->setMenu(nullptr);
     }
 }
 
@@ -304,7 +304,7 @@ QPlatformMenuItem * QMenuPrivate::insertActionInPlatformMenu(const QAction *acti
 int QMenuPrivate::scrollerHeight() const
 {
     Q_Q(const QMenu);
-    return qMax(QApplication::globalStrut().height(), q->style()->pixelMetric(QStyle::PM_MenuScrollerHeight, 0, q));
+    return qMax(QApplication::globalStrut().height(), q->style()->pixelMetric(QStyle::PM_MenuScrollerHeight, nullptr, q));
 }
 
 // Windows and KDE allow menus to cover the taskbar, while GNOME and macOS
@@ -541,9 +541,9 @@ void QMenuPrivate::hideUpToMenuBar()
         while(caused) {
 #if QT_CONFIG(menubar)
             if (QMenuBar *mb = qobject_cast<QMenuBar*>(caused)) {
-                mb->d_func()->setCurrentAction(0);
+                mb->d_func()->setCurrentAction(nullptr);
                 mb->d_func()->setKeyboardMode(false);
-                caused = 0;
+                caused = nullptr;
             } else
 #endif
             if (QMenu *m = qobject_cast<QMenu*>(caused)) {
@@ -551,12 +551,12 @@ void QMenuPrivate::hideUpToMenuBar()
                 if (!m->d_func()->tornoff)
                     hideMenu(m);
                 if (!fadeMenus) // Mac doesn't clear the action until after hidden.
-                    m->d_func()->setCurrentAction(0);
-            } else {                caused = 0;
+                    m->d_func()->setCurrentAction(nullptr);
+            } else {                caused = nullptr;
             }
         }
     }
-    setCurrentAction(0);
+    setCurrentAction(nullptr);
 }
 
 void QMenuPrivate::hideMenu(QMenu *menu)
@@ -573,7 +573,7 @@ void QMenuPrivate::hideMenu(QMenu *menu)
         QEventLoop eventLoop;
         QAction *activeAction = currentAction;
 
-        menu->setActiveAction(0);
+        menu->setActiveAction(nullptr);
         QTimer::singleShot(60, &eventLoop, SLOT(quit()));
         eventLoop.exec();
 
@@ -587,10 +587,10 @@ void QMenuPrivate::hideMenu(QMenu *menu)
     blocker.unblock();
 #endif // QT_CONFIG(effects)
     if (activeMenu == menu)
-        activeMenu = 0;
-    menu->d_func()->causedPopup.action = 0;
+        activeMenu = nullptr;
+    menu->d_func()->causedPopup.action = nullptr;
     menu->close();
-    menu->d_func()->causedPopup.widget = 0;
+    menu->d_func()->causedPopup.widget = nullptr;
 }
 
 void QMenuPrivate::popupAction(QAction *action, int delay, bool activateFirst)
@@ -617,7 +617,7 @@ void QMenuPrivate::setSyncAction()
     Q_Q(QMenu);
     QAction *current = currentAction;
     if(current && (!current->isEnabled() || current->menu() || current->isSeparator()))
-        current = 0;
+        current = nullptr;
     for(QWidget *caused = q; caused;) {
         if (QMenu *m = qobject_cast<QMenu*>(caused)) {
             caused = m->d_func()->causedPopup.widget;
@@ -645,7 +645,7 @@ void QMenuPrivate::setFirstActionActive()
         }
         QAction *act = actions.at(i);
         if (!act->isSeparator() &&
-           (q->style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, 0, q)
+           (q->style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, nullptr, q)
             || act->isEnabled())) {
             setCurrentAction(act);
             break;
@@ -661,7 +661,7 @@ void QMenuPrivate::setCurrentAction(QAction *action, int popup, SelectionReason
 
     if (action
             && (action->isSeparator()
-                || (!action->isEnabled() && !q->style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, 0, q))))
+                || (!action->isEnabled() && !q->style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, nullptr, q))))
         action = nullptr;
 
     // Reselect the currently active action in case mouse moved over other menu items when
@@ -718,8 +718,8 @@ void QMenuPrivate::setCurrentAction(QAction *action, int popup, SelectionReason
         if (popup == -1) {
 #if QT_CONFIG(effects)
             // kill any running effect
-            qFadeEffect(0);
-            qScrollEffect(0);
+            qFadeEffect(nullptr);
+            qScrollEffect(nullptr);
 #endif
             hideMenu(hideActiveMenu);
         } else if (!currentAction || !currentAction->menu()) {
@@ -867,13 +867,13 @@ QWidget *QMenuPrivate::topCausedWidget() const
 QAction *QMenuPrivate::actionAt(QPoint p) const
 {
     if (!rect().contains(p))     //sanity check
-       return 0;
+       return nullptr;
 
     for(int i = 0; i < actionRects.count(); i++) {
         if (actionRects.at(i).contains(p))
             return actions.at(i);
     }
-    return 0;
+    return nullptr;
 }
 
 void QMenuPrivate::setOverrideMenuAction(QAction *a)
@@ -976,7 +976,7 @@ QMenuPrivate::ScrollerTearOffItem::ScrollerTearOffItem(QMenuPrivate::ScrollerTea
     : QWidget(parent, f), menuPrivate(mPrivate), scrollType(type)
 {
     if (parent)
-        setMouseTracking(parent->style()->styleHint(QStyle::SH_Menu_MouseTracking, 0, parent));
+        setMouseTracking(parent->style()->styleHint(QStyle::SH_Menu_MouseTracking, nullptr, parent));
 }
 
 void QMenuPrivate::ScrollerTearOffItem::paintEvent(QPaintEvent *e)
@@ -991,7 +991,7 @@ void QMenuPrivate::ScrollerTearOffItem::paintEvent(QPaintEvent *e)
     menuPrivate->drawScroller(&p, scrollType, QRect(0, 0, width(), menuPrivate->scrollerHeight()));
     //paint the tear off
     if (scrollType == QMenuPrivate::ScrollerTearOffItem::ScrollUp) {
-        QRect rect(0, 0, width(), parent->style()->pixelMetric(QStyle::PM_MenuTearoffHeight, 0, parent));
+        QRect rect(0, 0, width(), parent->style()->pixelMetric(QStyle::PM_MenuTearoffHeight, nullptr, parent));
         if (menuPrivate->scroll && menuPrivate->scroll->scrollFlags & QMenuPrivate::QMenuScroller::ScrollUp)
             rect.translate(0, menuPrivate->scrollerHeight());
         menuPrivate->drawTearOff(&p, rect);
@@ -1066,8 +1066,8 @@ void QMenuPrivate::scrollMenu(QAction *action, QMenuScroller::ScrollLocation loc
     int newOffset = 0;
     const int topScroll = (scroll->scrollFlags & QMenuScroller::ScrollUp)   ? scrollerHeight() : 0;
     const int botScroll = (scroll->scrollFlags & QMenuScroller::ScrollDown) ? scrollerHeight() : 0;
-    const int vmargin = q->style()->pixelMetric(QStyle::PM_MenuVMargin, 0, q);
-    const int fw = q->style()->pixelMetric(QStyle::PM_MenuPanelWidth, 0, q);
+    const int vmargin = q->style()->pixelMetric(QStyle::PM_MenuVMargin, nullptr, q);
+    const int fw = q->style()->pixelMetric(QStyle::PM_MenuPanelWidth, nullptr, q);
 
     if (location == QMenuScroller::ScrollTop) {
         for(int i = 0, saccum = 0; i < actions.count(); i++) {
@@ -1108,7 +1108,7 @@ void QMenuPrivate::scrollMenu(QAction *action, QMenuScroller::ScrollLocation loc
     if (!(newScrollFlags & QMenuScroller::ScrollDown) && (scroll->scrollFlags & QMenuScroller::ScrollDown)) {
         newOffset = q->height() - (saccum - newOffset) - fw*2 - vmargin - topmargin - bottommargin;    //last item at bottom
         if (tearoff)
-            newOffset -= q->style()->pixelMetric(QStyle::PM_MenuTearoffHeight, 0, q);
+            newOffset -= q->style()->pixelMetric(QStyle::PM_MenuTearoffHeight, nullptr, q);
     }
 
     if (!(newScrollFlags & QMenuScroller::ScrollUp) && (scroll->scrollFlags & QMenuScroller::ScrollUp)) {
@@ -1119,7 +1119,7 @@ void QMenuPrivate::scrollMenu(QAction *action, QMenuScroller::ScrollLocation loc
         newOffset -= vmargin;
 
     QRect screen = popupGeometry();
-    const int desktopFrame = q->style()->pixelMetric(QStyle::PM_MenuDesktopFrameWidth, 0, q);
+    const int desktopFrame = q->style()->pixelMetric(QStyle::PM_MenuDesktopFrameWidth, nullptr, q);
     if (q->height() < screen.height()-(desktopFrame*2)-1) {
         QRect geom = q->geometry();
         if (newOffset > scroll->scrollOffset && (scroll->scrollFlags & newScrollFlags & QMenuScroller::ScrollUp)) { //scroll up
@@ -1181,7 +1181,7 @@ void QMenuPrivate::scrollMenu(QMenuScroller::ScrollLocation location, bool activ
             if (actionRects.at(i).isNull())
                 continue;
             if (!act->isSeparator() &&
-                (q->style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, 0, q)
+                (q->style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, nullptr, q)
                  || act->isEnabled())) {
                 if(scroll->scrollFlags & QMenuPrivate::QMenuScroller::ScrollDown)
                     scrollMenu(act, QMenuPrivate::QMenuScroller::ScrollBottom, active);
@@ -1196,7 +1196,7 @@ void QMenuPrivate::scrollMenu(QMenuScroller::ScrollLocation location, bool activ
             if (actionRects.at(i).isNull())
                 continue;
             if (!act->isSeparator() &&
-                (q->style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, 0, q)
+                (q->style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, nullptr, q)
                  || act->isEnabled())) {
                 if(scroll->scrollFlags & QMenuPrivate::QMenuScroller::ScrollUp)
                     scrollMenu(act, QMenuPrivate::QMenuScroller::ScrollTop, active);
@@ -1217,8 +1217,8 @@ void QMenuPrivate::scrollMenu(QMenuScroller::ScrollDirection direction, bool pag
     updateActionRects();
     const int topScroll = (scroll->scrollFlags & QMenuScroller::ScrollUp)   ? scrollerHeight() : 0;
     const int botScroll = (scroll->scrollFlags & QMenuScroller::ScrollDown) ? scrollerHeight() : 0;
-    const int vmargin = q->style()->pixelMetric(QStyle::PM_MenuVMargin, 0, q);
-    const int fw = q->style()->pixelMetric(QStyle::PM_MenuPanelWidth, 0, q);
+    const int vmargin = q->style()->pixelMetric(QStyle::PM_MenuVMargin, nullptr, q);
+    const int fw = q->style()->pixelMetric(QStyle::PM_MenuPanelWidth, nullptr, q);
     const int offset = topScroll ? topScroll-vmargin : 0;
     if (direction == QMenuScroller::ScrollUp) {
         for(int i = 0, saccum = 0; i < actions.count(); i++) {
@@ -1299,7 +1299,7 @@ bool QMenuPrivate::mouseEventTaken(QMouseEvent *e)
             tearRect.translate(0, scrollerHeight());
         q->update(tearRect);
         if (tearRect.contains(pos) && hasMouseMoved(e->globalPos())) {
-            setCurrentAction(0);
+            setCurrentAction(nullptr);
             tearoffHighlighted = 1;
             if (e->type() == QEvent::MouseButtonRelease) {
                 if (!tornPopup)
@@ -1318,7 +1318,7 @@ bool QMenuPrivate::mouseEventTaken(QMouseEvent *e)
 
     for(QWidget *caused = causedPopup.widget; caused;) {
         bool passOnEvent = false;
-        QWidget *next_widget = 0;
+        QWidget *next_widget = nullptr;
         QPoint cpos = caused->mapFromGlobal(e->globalPos());
 #if QT_CONFIG(menubar)
         if (QMenuBar *mb = qobject_cast<QMenuBar*>(caused)) {
@@ -1439,7 +1439,7 @@ void QMenuPrivate::activateAction(QAction *action, QAction::ActionEvent action_e
 #endif
         action->showStatusText(topCausedWidget());
     } else {
-        actionAboutToTrigger = 0;
+        actionAboutToTrigger = nullptr;
     }
 }
 
@@ -2258,7 +2258,7 @@ QAction *QMenu::actionAt(const QPoint &pt) const
 {
     if (QAction *ret = d_func()->actionAt(pt))
         return ret;
-    return 0;
+    return nullptr;
 }
 
 /*!
@@ -2380,7 +2380,7 @@ void QMenu::popup(const QPoint &p, QAction *atAction)
 
     const QSize menuSizeHint(sizeHint());
     QSize size = menuSizeHint;
-    const int desktopFrame = style()->pixelMetric(QStyle::PM_MenuDesktopFrameWidth, 0, this);
+    const int desktopFrame = style()->pixelMetric(QStyle::PM_MenuDesktopFrameWidth, nullptr, this);
     bool adjustToDesktop = !window()->testAttribute(Qt::WA_DontShowOnScreen);
 
     // if the screens have very different geometries and the menu is too big, we have to recalculate
@@ -2424,7 +2424,7 @@ void QMenu::popup(const QPoint &p, QAction *atAction)
                 pos.setY(newY);
 
                 if (d->scroll && d->scroll->scrollFlags != QMenuPrivate::QMenuScroller::ScrollNone
-                    && !style()->styleHint(QStyle::SH_Menu_FillScreenWithScroll, 0, this)) {
+                    && !style()->styleHint(QStyle::SH_Menu_FillScreenWithScroll, nullptr, this)) {
                     int below_height = above_height + d->scroll->scrollOffset;
                     for (int i2 = i; i2 < d->actionRects.count(); i2++)
                         below_height += d->actionRects.at(i2).height();
@@ -2483,7 +2483,7 @@ void QMenu::popup(const QPoint &p, QAction *atAction)
             }
         }
     }
-    const int subMenuOffset = style()->pixelMetric(QStyle::PM_SubMenuOverlap, 0, this);
+    const int subMenuOffset = style()->pixelMetric(QStyle::PM_SubMenuOverlap, nullptr, this);
     QMenu *caused = qobject_cast<QMenu*>(d_func()->causedPopup.widget);
     if (caused && caused->geometry().width() + menuSizeHint.width() + subMenuOffset < screen.width()) {
         QRect parentActionRect(caused->d_func()->actionRect(caused->d_func()->currentAction));
@@ -2553,8 +2553,8 @@ void QMenu::popup(const QPoint &p, QAction *atAction)
                 qScrollEffect(this, hGuess | vGuess);
         } else {
             // kill any running effect
-            qFadeEffect(0);
-            qScrollEffect(0);
+            qFadeEffect(nullptr);
+            qScrollEffect(nullptr);
 
             show();
         }
@@ -2690,22 +2690,22 @@ void QMenu::hideEvent(QHideEvent *)
     emit aboutToHide();
     if (d->eventLoop)
         d->eventLoop->exit();
-    d->setCurrentAction(0);
+    d->setCurrentAction(nullptr);
 #ifndef QT_NO_ACCESSIBILITY
     QAccessibleEvent event(this, QAccessible::PopupMenuEnd);
     QAccessible::updateAccessibility(&event);
 #endif
 #if QT_CONFIG(menubar)
     if (QMenuBar *mb = qobject_cast<QMenuBar*>(d->causedPopup.widget))
-        mb->d_func()->setCurrentAction(0);
+        mb->d_func()->setCurrentAction(nullptr);
 #endif
     if (QMenuPrivate::mouseDown == this)
         QMenuPrivate::mouseDown = nullptr;
     d->hasHadMouse = false;
     if (d->activeMenu)
         d->hideMenu(d->activeMenu);
-    d->causedPopup.widget = 0;
-    d->causedPopup.action = 0;
+    d->causedPopup.widget = nullptr;
+    d->causedPopup.action = nullptr;
     if (d->scroll)
         d->scroll->scrollTimer.stop(); //make sure the timer stops
 }
@@ -2729,9 +2729,9 @@ void QMenu::paintEvent(QPaintEvent *e)
     style()->drawPrimitive(QStyle::PE_PanelMenu, &menuOpt, &p, this);
 
     //calculate the scroll up / down rect
-    const int fw = style()->pixelMetric(QStyle::PM_MenuPanelWidth, 0, this);
-    const int hmargin = style()->pixelMetric(QStyle::PM_MenuHMargin,0, this);
-    const int vmargin = style()->pixelMetric(QStyle::PM_MenuVMargin, 0, this);
+    const int fw = style()->pixelMetric(QStyle::PM_MenuPanelWidth, nullptr, this);
+    const int hmargin = style()->pixelMetric(QStyle::PM_MenuHMargin,nullptr, this);
+    const int vmargin = style()->pixelMetric(QStyle::PM_MenuVMargin, nullptr, this);
 
     QRect scrollUpRect, scrollDownRect;
     const int leftmargin = fw + hmargin + d->leftmargin;
@@ -2751,7 +2751,7 @@ void QMenu::paintEvent(QPaintEvent *e)
     QRect tearOffRect;
     if (d->tearoff) {
         tearOffRect.setRect(leftmargin, topmargin, contentWidth,
-                            style()->pixelMetric(QStyle::PM_MenuTearoffHeight, 0, this));
+                            style()->pixelMetric(QStyle::PM_MenuTearoffHeight, nullptr, this));
         if (d->scroll && d->scroll->scrollFlags & QMenuPrivate::QMenuScroller::ScrollUp)
             tearOffRect.translate(0, d->scrollerHeight());
     }
@@ -2871,7 +2871,7 @@ void QMenu::mousePressEvent(QMouseEvent *e)
              && QRect(d->noReplayFor->mapToGlobal(QPoint()), d->noReplayFor->size()).contains(e->globalPos()))
              setAttribute(Qt::WA_NoMouseReplay);
          if (d->eventLoop) // synchronous operation
-             d->syncAction = 0;
+             d->syncAction = nullptr;
         d->hideUpToMenuBar();
         return;
     }
@@ -2921,12 +2921,12 @@ void QMenu::changeEvent(QEvent *e)
     if (e->type() == QEvent::StyleChange || e->type() == QEvent::FontChange ||
         e->type() == QEvent::LayoutDirectionChange) {
         d->itemsDirty = 1;
-        setMouseTracking(style()->styleHint(QStyle::SH_Menu_MouseTracking, 0, this));
+        setMouseTracking(style()->styleHint(QStyle::SH_Menu_MouseTracking, nullptr, this));
         if (isVisible())
             resize(sizeHint());
-        if (!style()->styleHint(QStyle::SH_Menu_Scrollable, 0, this)) {
+        if (!style()->styleHint(QStyle::SH_Menu_Scrollable, nullptr, this)) {
             delete d->scroll;
-            d->scroll = 0;
+            d->scroll = nullptr;
         } else if (!d->scroll) {
             d->scroll = new QMenuPrivate::QMenuScroller;
             d->scroll->scrollFlags = QMenuPrivate::QMenuScroller::ScrollNone;
@@ -3095,7 +3095,7 @@ void QMenu::keyPressEvent(QKeyEvent *e)
     case Qt::Key_Up:
     case Qt::Key_Down: {
         key_consumed = true;
-        QAction *nextAction = 0;
+        QAction *nextAction = nullptr;
         QMenuPrivate::QMenuScroller::ScrollLocation scroll_loc = QMenuPrivate::QMenuScroller::ScrollStay;
         if (!d->currentAction) {
             if(key == Qt::Key_Down) {
@@ -3104,7 +3104,7 @@ void QMenu::keyPressEvent(QKeyEvent *e)
                     if (d->actionRects.at(i).isNull())
                         continue;
                     if (!act->isSeparator() &&
-                        (style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, 0, this)
+                        (style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, nullptr, this)
                          || act->isEnabled())) {
                         nextAction = act;
                         break;
@@ -3116,7 +3116,7 @@ void QMenu::keyPressEvent(QKeyEvent *e)
                     if (d->actionRects.at(i).isNull())
                         continue;
                     if (!act->isSeparator() &&
-                        (style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, 0, this)
+                        (style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, nullptr, this)
                          || act->isEnabled())) {
                         nextAction = act;
                         break;
@@ -3130,7 +3130,7 @@ void QMenu::keyPressEvent(QKeyEvent *e)
                     if (key == Qt::Key_Up) {
                         for(int next_i = i-1; true; next_i--) {
                             if (next_i == -1) {
-                                if(!style()->styleHint(QStyle::SH_Menu_SelectionWrap, 0, this))
+                                if (!style()->styleHint(QStyle::SH_Menu_SelectionWrap, nullptr, this))
                                     break;
                                 if (d->scroll)
                                     scroll_loc = QMenuPrivate::QMenuScroller::ScrollBottom;
@@ -3143,13 +3143,13 @@ void QMenu::keyPressEvent(QKeyEvent *e)
                                 continue;
                             if (next->isSeparator() ||
                                (!next->isEnabled() &&
-                                !style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, 0, this)))
+                                !style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, nullptr, this)))
                                 continue;
                             nextAction = next;
                             if (d->scroll && (d->scroll->scrollFlags & QMenuPrivate::QMenuScroller::ScrollUp)) {
                                 int topVisible = d->scrollerHeight();
                                 if (d->tearoff)
-                                    topVisible += style()->pixelMetric(QStyle::PM_MenuTearoffHeight, 0, this);
+                                    topVisible += style()->pixelMetric(QStyle::PM_MenuTearoffHeight, nullptr, this);
                                 if (((y + d->scroll->scrollOffset) - topVisible) <= d->actionRects.at(next_i).height())
                                     scroll_loc = QMenuPrivate::QMenuScroller::ScrollTop;
                             }
@@ -3161,7 +3161,7 @@ void QMenu::keyPressEvent(QKeyEvent *e)
                         y += d->actionRects.at(i).height();
                         for(int next_i = i+1; true; next_i++) {
                             if (next_i == d->actionRects.count()) {
-                                if(!style()->styleHint(QStyle::SH_Menu_SelectionWrap, 0, this))
+                                if (!style()->styleHint(QStyle::SH_Menu_SelectionWrap, nullptr, this))
                                     break;
                                 if (d->scroll)
                                     scroll_loc = QMenuPrivate::QMenuScroller::ScrollTop;
@@ -3174,7 +3174,7 @@ void QMenu::keyPressEvent(QKeyEvent *e)
                                 continue;
                             if (next->isSeparator() ||
                                (!next->isEnabled() &&
-                                !style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, 0, this)))
+                                !style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, nullptr, this)))
                                 continue;
                             nextAction = next;
                             if (d->scroll && (d->scroll->scrollFlags & QMenuPrivate::QMenuScroller::ScrollDown)) {
@@ -3182,7 +3182,7 @@ void QMenu::keyPressEvent(QKeyEvent *e)
                                 if (d->scroll->scrollFlags & QMenuPrivate::QMenuScroller::ScrollUp)
                                     bottomVisible -= d->scrollerHeight();
                                 if (d->tearoff)
-                                    bottomVisible -= style()->pixelMetric(QStyle::PM_MenuTearoffHeight, 0, this);
+                                    bottomVisible -= style()->pixelMetric(QStyle::PM_MenuTearoffHeight, nullptr, this);
                                 if ((y + d->scroll->scrollOffset + d->actionRects.at(next_i).height()) > bottomVisible)
                                     scroll_loc = QMenuPrivate::QMenuScroller::ScrollBottom;
                             }
@@ -3212,7 +3212,7 @@ void QMenu::keyPressEvent(QKeyEvent *e)
         Q_FALLTHROUGH();
     case Qt::Key_Left: {
         if (d->currentAction && !d->scroll) {
-            QAction *nextAction = 0;
+            QAction *nextAction = nullptr;
             if (key == Qt::Key_Left) {
                 QRect actionR = d->actionRect(d->currentAction);
                 for(int x = actionR.left()-1; !nextAction && x >= 0; x--)
@@ -3241,7 +3241,7 @@ void QMenu::keyPressEvent(QKeyEvent *e)
             break;
 
         key_consumed = true;
-        if (style()->styleHint(QStyle::SH_MenuBar_AltKeyNavigation, 0, this))
+        if (style()->styleHint(QStyle::SH_MenuBar_AltKeyNavigation, nullptr, this))
         {
             d->hideMenu(this);
 #if QT_CONFIG(menubar)
@@ -3253,7 +3253,7 @@ void QMenu::keyPressEvent(QKeyEvent *e)
         break;
 
     case Qt::Key_Space:
-        if (!style()->styleHint(QStyle::SH_Menu_SpaceActivatesItem, 0, this))
+        if (!style()->styleHint(QStyle::SH_Menu_SpaceActivatesItem, nullptr, this))
             break;
         // for motif, fall through
         Q_FALLTHROUGH();
@@ -3319,8 +3319,8 @@ void QMenu::keyPressEvent(QKeyEvent *e)
         if ((!e->modifiers() || e->modifiers() == Qt::AltModifier || e->modifiers() == Qt::ShiftModifier) &&
            e->text().length()==1) {
             bool activateAction = false;
-            QAction *nextAction = 0;
-            if (style()->styleHint(QStyle::SH_Menu_KeyboardSearch, 0, this) && !e->modifiers()) {
+            QAction *nextAction = nullptr;
+            if (style()->styleHint(QStyle::SH_Menu_KeyboardSearch, nullptr, this) && !e->modifiers()) {
                 int best_match_count = 0;
                 d->searchBufferTimer.start(2000, this);
                 d->searchBuffer += e->text();
@@ -3343,7 +3343,7 @@ void QMenu::keyPressEvent(QKeyEvent *e)
 #ifndef QT_NO_SHORTCUT
             else {
                 int clashCount = 0;
-                QAction *first = 0, *currentSelected = 0, *firstAfterCurrent = 0;
+                QAction *first = nullptr, *currentSelected = nullptr, *firstAfterCurrent = nullptr;
                 QChar c = e->text().at(0).toUpper();
                 for(int i = 0; i < d->actions.size(); ++i) {
                     if (d->actionRects.at(i).isNull())
@@ -3432,7 +3432,7 @@ void QMenu::mouseMoveEvent(QMouseEvent *e)
         QMenuPrivate::mouseDown = this;
 
     if (d->activeMenu)
-        d->activeMenu->d_func()->setCurrentAction(0);
+        d->activeMenu->d_func()->setCurrentAction(nullptr);
 
     QMenuSloppyState::MouseEventResult sloppyEventResult = d->sloppyState.processMouseEvent(e->localPos(), action, d->currentAction);
     if (sloppyEventResult == QMenuSloppyState::EventShouldBePropagated) {
@@ -3462,7 +3462,7 @@ void QMenu::leaveEvent(QEvent *)
     Q_D(QMenu);
     d->hasReceievedEnter = false;
     if (!d->activeMenu && d->currentAction)
-        setActiveAction(0);
+        setActiveAction(nullptr);
 }
 
 /*!
@@ -3525,7 +3525,7 @@ void QMenu::actionEvent(QActionEvent *e)
     } else if (e->type() == QEvent::ActionRemoved) {
         e->action()->disconnect(this);
         if (e->action() == d->currentAction)
-            d->currentAction = 0;
+            d->currentAction = nullptr;
         if (QWidgetAction *wa = qobject_cast<QWidgetAction *>(e->action())) {
             if (QWidget *widget = d->widgetItems.value(wa)) {
 #ifdef Q_OS_OSX
@@ -3601,7 +3601,7 @@ void QMenu::internalDelayedPopup()
 #endif
     screen = d->popupGeometry(QDesktopWidgetPrivate::screenNumber(pos()));
 
-    int subMenuOffset = style()->pixelMetric(QStyle::PM_SubMenuOverlap, 0, this);
+    int subMenuOffset = style()->pixelMetric(QStyle::PM_SubMenuOverlap, nullptr, this);
     const QRect actionRect(d->actionRect(d->currentAction));
     QPoint subMenuPos(mapToGlobal(QPoint(actionRect.right() + subMenuOffset + 1, actionRect.top())));
     if (subMenuPos.x() > screen.right())
diff --git a/src/widgets/widgets/qmenubar.cpp b/src/widgets/widgets/qmenubar.cpp
index afa5ca7142..2de7cdff71 100644
--- a/src/widgets/widgets/qmenubar.cpp
+++ b/src/widgets/widgets/qmenubar.cpp
@@ -90,7 +90,7 @@ QMenuBarExtension::QMenuBarExtension(QWidget *parent)
 #if QT_CONFIG(menu)
     setPopupMode(QToolButton::InstantPopup);
 #endif
-    setIcon(style()->standardIcon(QStyle::SP_ToolBarHorizontalExtensionButton, 0, parentWidget()));
+    setIcon(style()->standardIcon(QStyle::SP_ToolBarHorizontalExtensionButton, nullptr, parentWidget()));
 }
 
 void QMenuBarExtension::paintEvent(QPaintEvent *)
@@ -106,7 +106,7 @@ void QMenuBarExtension::paintEvent(QPaintEvent *)
 
 QSize QMenuBarExtension::sizeHint() const
 {
-    int ext = style()->pixelMetric(QStyle::PM_ToolBarExtensionExtent, 0, parentWidget());
+    int ext = style()->pixelMetric(QStyle::PM_ToolBarExtensionExtent, nullptr, parentWidget());
     return QSize(ext, ext);
 }
 
@@ -120,14 +120,14 @@ QAction *QMenuBarPrivate::actionAt(QPoint p) const
         if(actionRect(actions.at(i)).contains(p))
             return actions.at(i);
     }
-    return 0;
+    return nullptr;
 }
 
 QRect QMenuBarPrivate::menuRect(bool extVisible) const
 {
     Q_Q(const QMenuBar);
 
-    int hmargin = q->style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, 0, q);
+    int hmargin = q->style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, nullptr, q);
     QRect result = q->rect();
     result.adjust(hmargin, 0, -hmargin, 0);
 
@@ -167,13 +167,13 @@ void QMenuBarPrivate::updateGeometries()
     Q_Q(QMenuBar);
     if(!itemsDirty)
         return;
-    int q_width = q->width()-(q->style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, 0, q)*2);
+    int q_width = q->width()-(q->style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, nullptr, q)*2);
     int q_start = -1;
     if(leftWidget || rightWidget) {
-        int vmargin = q->style()->pixelMetric(QStyle::PM_MenuBarVMargin, 0, q)
-                      + q->style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, 0, q);
-        int hmargin = q->style()->pixelMetric(QStyle::PM_MenuBarHMargin, 0, q)
-                      + q->style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, 0, q);
+        int vmargin = q->style()->pixelMetric(QStyle::PM_MenuBarVMargin, nullptr, q)
+                      + q->style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, nullptr, q);
+        int hmargin = q->style()->pixelMetric(QStyle::PM_MenuBarHMargin, nullptr, q)
+                      + q->style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, nullptr, q);
         if (leftWidget && leftWidget->isVisible()) {
             QSize sz = leftWidget->sizeHint();
             q_width -= sz.width();
@@ -198,7 +198,7 @@ void QMenuBarPrivate::updateGeometries()
     }
 #endif
     calcActionRects(q_width, q_start);
-    currentAction = 0;
+    currentAction = nullptr;
 #ifndef QT_NO_SHORTCUT
     if(itemsDirty) {
         for(int j = 0; j < shortcutIndexMap.size(); ++j)
@@ -246,7 +246,7 @@ void QMenuBarPrivate::updateGeometries()
         pop->clear();
         pop->addActions(hiddenActions);
 
-        int vmargin = q->style()->pixelMetric(QStyle::PM_MenuBarVMargin, 0, q);
+        int vmargin = q->style()->pixelMetric(QStyle::PM_MenuBarVMargin, nullptr, q);
         int x = q->isRightToLeft()
                 ? menuRect.left() - extension->sizeHint().width() + 1
                 : menuRect.right();
@@ -285,8 +285,8 @@ void QMenuBarPrivate::focusFirstAction()
 void QMenuBarPrivate::setKeyboardMode(bool b)
 {
     Q_Q(QMenuBar);
-    if (b && !q->style()->styleHint(QStyle::SH_MenuBar_AltKeyNavigation, 0, q)) {
-        setCurrentAction(0);
+    if (b && !q->style()->styleHint(QStyle::SH_MenuBar_AltKeyNavigation, nullptr, q)) {
+        setCurrentAction(nullptr);
         return;
     }
     keyboardState = b;
@@ -298,11 +298,11 @@ void QMenuBarPrivate::setKeyboardMode(bool b)
         q->setFocus(Qt::MenuBarFocusReason);
     } else {
         if(!popupState)
-            setCurrentAction(0);
+            setCurrentAction(nullptr);
         if(keyboardFocusWidget) {
             if (QApplication::focusWidget() == q)
                 keyboardFocusWidget->setFocus(Qt::MenuBarFocusReason);
-            keyboardFocusWidget = 0;
+            keyboardFocusWidget = nullptr;
         }
     }
     q->update();
@@ -372,9 +372,9 @@ void QMenuBarPrivate::setCurrentAction(QAction *action, bool popup, bool activat
 
     doChildEffects = (popup && !activeMenu);
     Q_Q(QMenuBar);
-    QWidget *fw = 0;
+    QWidget *fw = nullptr;
     if(QMenu *menu = activeMenu) {
-        activeMenu = 0;
+        activeMenu = nullptr;
         if (popup) {
             fw = q->window()->focusWidget();
             q->setFocus(Qt::NoFocusReason);
@@ -419,14 +419,14 @@ void QMenuBarPrivate::calcActionRects(int max_width, int start) const
 
     const QStyle *style = q->style();
 
-    const int itemSpacing = style->pixelMetric(QStyle::PM_MenuBarItemSpacing, 0, q);
+    const int itemSpacing = style->pixelMetric(QStyle::PM_MenuBarItemSpacing, nullptr, q);
     int max_item_height = 0, separator = -1, separator_start = 0, separator_len = 0;
 
     //calculate size
     const QFontMetrics fm = q->fontMetrics();
-    const int hmargin = style->pixelMetric(QStyle::PM_MenuBarHMargin, 0, q),
-              vmargin = style->pixelMetric(QStyle::PM_MenuBarVMargin, 0, q),
-                icone = style->pixelMetric(QStyle::PM_SmallIconSize, 0, q);
+    const int hmargin = style->pixelMetric(QStyle::PM_MenuBarHMargin, nullptr, q),
+              vmargin = style->pixelMetric(QStyle::PM_MenuBarVMargin, nullptr, q),
+                icone = style->pixelMetric(QStyle::PM_SmallIconSize, nullptr, q);
     for(int i = 0; i < actions.count(); i++) {
         QAction *action = actions.at(i);
         if(!action->isVisible())
@@ -436,7 +436,7 @@ void QMenuBarPrivate::calcActionRects(int max_width, int start) const
 
         //calc what I think the size is..
         if(action->isSeparator()) {
-            if (style->styleHint(QStyle::SH_DrawMenuBarSeparator, 0, q))
+            if (style->styleHint(QStyle::SH_DrawMenuBarSeparator, nullptr, q))
                 separator = i;
             continue; //we don't really position these!
         } else {
@@ -470,7 +470,7 @@ void QMenuBarPrivate::calcActionRects(int max_width, int start) const
     }
 
     //calculate position
-    const int fw = q->style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, 0, q);
+    const int fw = q->style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, nullptr, q);
     int x = fw + ((start == -1) ? hmargin : start) + itemSpacing;
     int y = fw + vmargin;
     for(int i = 0; i < actions.count(); i++) {
@@ -703,7 +703,7 @@ void QMenuBarPrivate::init()
         q->hide();
     q->setBackgroundRole(QPalette::Button);
     handleReparent();
-    q->setMouseTracking(q->style()->styleHint(QStyle::SH_MenuBar_MouseTracking, 0, q));
+    q->setMouseTracking(q->style()->styleHint(QStyle::SH_MenuBar_MouseTracking, nullptr, q));
 
     extension = new QMenuBarExtension(q);
     extension->setFocusPolicy(Qt::NoFocus);
@@ -715,7 +715,7 @@ QAction *QMenuBarPrivate::getNextAction(const int _start, const int increment) c
 {
     Q_Q(const QMenuBar);
     const_cast<QMenuBarPrivate*>(this)->updateGeometries();
-    bool allowActiveAndDisabled = q->style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, 0, q);
+    bool allowActiveAndDisabled = q->style()->styleHint(QStyle::SH_Menu_AllowActiveAndDisabled, nullptr, q);
     const int start = (_start == -1 && increment == -1) ? actions.count() : _start;
     const int end =  increment == -1 ? 0 : actions.count() - 1;
 
@@ -729,7 +729,7 @@ QAction *QMenuBarPrivate::getNextAction(const int _start, const int increment) c
     if (_start != -1) //let's try from the beginning or the end
         return getNextAction(-1, increment);
 
-    return 0;
+    return nullptr;
 }
 
 /*!
@@ -749,7 +749,7 @@ QMenuBar::~QMenuBar()
 {
     Q_D(QMenuBar);
     delete d->platformMenuBar;
-    d->platformMenuBar = 0;
+    d->platformMenuBar = nullptr;
 }
 
 /*!
@@ -1001,7 +1001,7 @@ void QMenuBar::paintEvent(QPaintEvent *e)
         style()->drawControl(QStyle::CE_MenuBarItem, &opt, &p, this);
     }
      //draw border
-    if(int fw = style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, 0, this)) {
+    if (int fw = style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, nullptr, this)) {
         QRegion borderReg;
         borderReg += QRect(0, 0, fw, height()); //left
         borderReg += QRect(width()-fw, 0, fw, height()); //right
@@ -1054,7 +1054,7 @@ void QMenuBar::mousePressEvent(QMouseEvent *e)
 
     QAction *action = d->actionAt(e->pos());
     if (!action || !d->isVisible(action) || !action->isEnabled()) {
-        d->setCurrentAction(0);
+        d->setCurrentAction(nullptr);
 #if QT_CONFIG(whatsthis)
         if (QWhatsThis::inWhatsThisMode())
             QWhatsThis::showText(e->globalPos(), d->whatsThis, this);
@@ -1064,7 +1064,7 @@ void QMenuBar::mousePressEvent(QMouseEvent *e)
 
     if(d->currentAction == action && d->popupState) {
         if(QMenu *menu = d->activeMenu) {
-            d->activeMenu = 0;
+            d->activeMenu = nullptr;
             menu->setAttribute(Qt::WA_NoMouseReplay);
             menu->hide();
         }
@@ -1124,7 +1124,7 @@ void QMenuBar::keyPressEvent(QKeyEvent *e)
     case Qt::Key_Enter:
     case Qt::Key_Space:
     case Qt::Key_Return: {
-        if(!style()->styleHint(QStyle::SH_MenuBar_AltKeyNavigation, 0, this) || !d->currentAction)
+        if (!style()->styleHint(QStyle::SH_MenuBar_AltKeyNavigation, nullptr, this) || !d->currentAction)
            break;
         if(d->currentAction->menu()) {
             d->popupAction(d->currentAction, true);
@@ -1153,7 +1153,7 @@ void QMenuBar::keyPressEvent(QKeyEvent *e)
 
 #ifndef QT_NO_SHORTCUT
     if (!key_consumed && e->matches(QKeySequence::Cancel)) {
-        d->setCurrentAction(0);
+        d->setCurrentAction(nullptr);
         d->setKeyboardMode(false);
         key_consumed = true;
     }
@@ -1163,7 +1163,7 @@ void QMenuBar::keyPressEvent(QKeyEvent *e)
        (!e->modifiers() ||
         (e->modifiers()&(Qt::MetaModifier|Qt::AltModifier))) && e->text().length()==1 && !d->popupState) {
         int clashCount = 0;
-        QAction *first = 0, *currentSelected = 0, *firstAfterCurrent = 0;
+        QAction *first = nullptr, *currentSelected = nullptr, *firstAfterCurrent = nullptr;
         {
             const QChar c = e->text().at(0).toUpper();
             for(int i = 0; i < d->actions.size(); ++i) {
@@ -1187,7 +1187,7 @@ void QMenuBar::keyPressEvent(QKeyEvent *e)
                 }
             }
         }
-        QAction *next_action = 0;
+        QAction *next_action = nullptr;
         if(clashCount >= 1) {
             if(clashCount == 1 || !d->currentAction || (currentSelected && !firstAfterCurrent))
                 next_action = first;
@@ -1233,14 +1233,14 @@ void QMenuBar::leaveEvent(QEvent *)
 {
     Q_D(QMenuBar);
     if((!hasFocus() && !d->popupState) ||
-        (d->currentAction && d->currentAction->menu() == 0))
-        d->setCurrentAction(0);
+        (d->currentAction && d->currentAction->menu() == nullptr))
+        d->setCurrentAction(nullptr);
 }
 
 QPlatformMenu *QMenuBarPrivate::getPlatformMenu(const QAction *action)
 {
     if (!action || !action->menu())
-        return 0;
+        return nullptr;
 
     QPlatformMenu *platformMenu = action->menu()->platformMenu();
     if (!platformMenu && platformMenuBar) {
@@ -1353,7 +1353,7 @@ void QMenuBar::focusOutEvent(QFocusEvent *)
 {
     Q_D(QMenuBar);
     if(!d->popupState) {
-        d->setCurrentAction(0);
+        d->setCurrentAction(nullptr);
         d->setKeyboardMode(false);
     }
 }
@@ -1366,7 +1366,7 @@ void QMenuBar::timerEvent (QTimerEvent *e)
     Q_D(QMenuBar);
     if (e->timerId() == d->autoReleaseTimer.timerId()) {
         d->autoReleaseTimer.stop();
-        d->setCurrentAction(0);
+        d->setCurrentAction(nullptr);
     }
     QWidget::timerEvent(e);
 }
@@ -1420,7 +1420,7 @@ void QMenuBarPrivate::handleReparent()
             newWindow->createWinId();
             platformMenuBar->handleReparent(newWindow->windowHandle());
         } else {
-            platformMenuBar->handleReparent(0);
+            platformMenuBar->handleReparent(nullptr);
         }
     }
 }
@@ -1433,7 +1433,7 @@ void QMenuBar::changeEvent(QEvent *e)
     Q_D(QMenuBar);
     if(e->type() == QEvent::StyleChange) {
         d->itemsDirty = true;
-        setMouseTracking(style()->styleHint(QStyle::SH_MenuBar_MouseTracking, 0, this));
+        setMouseTracking(style()->styleHint(QStyle::SH_MenuBar_MouseTracking, nullptr, this));
         if(parentWidget())
             resize(parentWidget()->width(), heightForWidth(parentWidget()->width()));
         d->updateGeometries();
@@ -1542,7 +1542,7 @@ bool QMenuBar::eventFilter(QObject *object, QEvent *event)
             d->platformMenuBar->handleReparent(handle);
     }
 
-    if (style()->styleHint(QStyle::SH_MenuBar_AltKeyNavigation, 0, this)) {
+    if (style()->styleHint(QStyle::SH_MenuBar_AltKeyNavigation, nullptr, this)) {
         if (d->altPressed) {
             switch (event->type()) {
             case QEvent::KeyPress:
@@ -1618,10 +1618,10 @@ QSize QMenuBar::minimumSizeHint() const
     ensurePolished();
     QSize ret(0, 0);
     const_cast<QMenuBarPrivate*>(d)->updateGeometries();
-    const int hmargin = style()->pixelMetric(QStyle::PM_MenuBarHMargin, 0, this);
-    const int vmargin = style()->pixelMetric(QStyle::PM_MenuBarVMargin, 0, this);
-    int fw = style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, 0, this);
-    int spaceBelowMenuBar = style()->styleHint(QStyle::SH_MainWindow_SpaceBelowMenuBar, 0, this);
+    const int hmargin = style()->pixelMetric(QStyle::PM_MenuBarHMargin, nullptr, this);
+    const int vmargin = style()->pixelMetric(QStyle::PM_MenuBarVMargin, nullptr, this);
+    int fw = style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, nullptr, this);
+    int spaceBelowMenuBar = style()->styleHint(QStyle::SH_MainWindow_SpaceBelowMenuBar, nullptr, this);
     if(as_gui_menubar) {
         int w = parentWidget() ? parentWidget()->width() : QDesktopWidgetPrivate::width();
         d->calcActionRects(w - (2 * fw), 0);
@@ -1670,10 +1670,10 @@ QSize QMenuBar::sizeHint() const
     ensurePolished();
     QSize ret(0, 0);
     const_cast<QMenuBarPrivate*>(d)->updateGeometries();
-    const int hmargin = style()->pixelMetric(QStyle::PM_MenuBarHMargin, 0, this);
-    const int vmargin = style()->pixelMetric(QStyle::PM_MenuBarVMargin, 0, this);
-    int fw = style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, 0, this);
-    int spaceBelowMenuBar = style()->styleHint(QStyle::SH_MainWindow_SpaceBelowMenuBar, 0, this);
+    const int hmargin = style()->pixelMetric(QStyle::PM_MenuBarHMargin, nullptr, this);
+    const int vmargin = style()->pixelMetric(QStyle::PM_MenuBarVMargin, nullptr, this);
+    int fw = style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, nullptr, this);
+    int spaceBelowMenuBar = style()->styleHint(QStyle::SH_MainWindow_SpaceBelowMenuBar, nullptr, this);
     if(as_gui_menubar) {
         const int w = parentWidget() ? parentWidget()->width() : QDesktopWidgetPrivate::width();
         d->calcActionRects(w - (2 * fw), 0);
@@ -1722,9 +1722,9 @@ int QMenuBar::heightForWidth(int) const
 
     const_cast<QMenuBarPrivate*>(d)->updateGeometries();
     int height = 0;
-    const int vmargin = style()->pixelMetric(QStyle::PM_MenuBarVMargin, 0, this);
-    int fw = style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, 0, this);
-    int spaceBelowMenuBar = style()->styleHint(QStyle::SH_MainWindow_SpaceBelowMenuBar, 0, this);
+    const int vmargin = style()->pixelMetric(QStyle::PM_MenuBarVMargin, nullptr, this);
+    int fw = style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, nullptr, this);
+    int spaceBelowMenuBar = style()->styleHint(QStyle::SH_MainWindow_SpaceBelowMenuBar, nullptr, this);
     if(as_gui_menubar) {
         for (int i = 0; i < d->actionRects.count(); ++i)
             height = qMax(height, d->actionRects.at(i).height());
@@ -1770,7 +1770,7 @@ void QMenuBarPrivate::_q_internalShortcutActivated(int id)
         activateAction(act, QAction::Trigger);
         //100 is the same as the default value in QPushButton::animateClick
         autoReleaseTimer.start(100, q);
-    } else if (act && q->style()->styleHint(QStyle::SH_MenuBar_AltKeyNavigation, 0, q)) {
+    } else if (act && q->style()->styleHint(QStyle::SH_MenuBar_AltKeyNavigation, nullptr, q)) {
         // When we open a menu using a shortcut, we should end up in keyboard state
         setKeyboardMode(true);
     }
@@ -1836,7 +1836,7 @@ void QMenuBar::setCornerWidget(QWidget *w, Qt::Corner corner)
 QWidget *QMenuBar::cornerWidget(Qt::Corner corner) const
 {
     Q_D(const QMenuBar);
-    QWidget *w = 0;
+    QWidget *w = nullptr;
     switch(corner) {
     case Qt::TopLeftCorner:
         w = d->leftWidget;
@@ -1875,7 +1875,7 @@ void QMenuBar::setNativeMenuBar(bool nativeMenuBar)
     if (nativeMenuBar != bool(d->platformMenuBar)) {
         if (!nativeMenuBar) {
             delete d->platformMenuBar;
-            d->platformMenuBar = 0;
+            d->platformMenuBar = nullptr;
         } else {
             if (!d->platformMenuBar)
                 d->platformMenuBar = QGuiApplicationPrivate::platformTheme()->createPlatformMenuBar();
diff --git a/src/widgets/widgets/qplaintextedit.cpp b/src/widgets/widgets/qplaintextedit.cpp
index 0a81931b57..1856f0296b 100644
--- a/src/widgets/widgets/qplaintextedit.cpp
+++ b/src/widgets/widgets/qplaintextedit.cpp
@@ -81,7 +81,7 @@ class QPlainTextDocumentLayoutPrivate : public QAbstractTextDocumentLayoutPrivat
     Q_DECLARE_PUBLIC(QPlainTextDocumentLayout)
 public:
     QPlainTextDocumentLayoutPrivate() {
-        mainViewPrivate = 0;
+        mainViewPrivate = nullptr;
         width = 0;
         maximumWidth = 0;
         maximumWidthBlockNumber = 0;
@@ -755,7 +755,7 @@ void QPlainTextEditPrivate::updateViewport()
 }
 
 QPlainTextEditPrivate::QPlainTextEditPrivate()
-    : control(0),
+    : control(nullptr),
       tabChangesFocus(false),
       lineWrap(QPlainTextEdit::WidgetWidth),
       wordWrap(QTextOption::WrapAtWordBoundaryOrAnywhere),
@@ -1302,7 +1302,7 @@ QPlainTextEdit::~QPlainTextEdit()
     Q_D(QPlainTextEdit);
     if (d->documentLayoutPtr) {
         if (d->documentLayoutPtr->priv()->mainViewPrivate == d)
-            d->documentLayoutPtr->priv()->mainViewPrivate = 0;
+            d->documentLayoutPtr->priv()->mainViewPrivate = nullptr;
     }
 }
 
@@ -1321,7 +1321,7 @@ QPlainTextEdit::~QPlainTextEdit()
 void QPlainTextEdit::setDocument(QTextDocument *document)
 {
     Q_D(QPlainTextEdit);
-    QPlainTextDocumentLayout *documentLayout = 0;
+    QPlainTextDocumentLayout *documentLayout = nullptr;
 
     if (!document) {
         document = new QTextDocument(d->control);
@@ -1891,7 +1891,7 @@ void QPlainTextEditPrivate::relayoutDocument()
 
     int width = viewport->width();
 
-    if (documentLayout->priv()->mainViewPrivate == 0
+    if (documentLayout->priv()->mainViewPrivate == nullptr
         || documentLayout->priv()->mainViewPrivate == this
         || width > documentLayout->textWidth()) {
         documentLayout->priv()->mainViewPrivate = this;
diff --git a/src/widgets/widgets/qpushbutton.cpp b/src/widgets/widgets/qpushbutton.cpp
index f48b5706f7..b0d3ba51f9 100644
--- a/src/widgets/widgets/qpushbutton.cpp
+++ b/src/widgets/widgets/qpushbutton.cpp
@@ -297,7 +297,7 @@ QDialog *QPushButtonPrivate::dialogParent() const
         if (const QDialog *dialog = qobject_cast<const QDialog *>(p))
             return const_cast<QDialog *>(dialog);
     }
-    return 0;
+    return nullptr;
 }
 #endif
 
@@ -353,7 +353,7 @@ bool QPushButton::autoDefault() const
 {
     Q_D(const QPushButton);
     if(d->autoDefault == QPushButtonPrivate::Auto)
-        return ( d->dialogParent() != 0 );
+        return ( d->dialogParent() != nullptr );
     return d->autoDefault;
 }
 
@@ -496,7 +496,7 @@ void QPushButton::focusOutEvent(QFocusEvent *e)
 #if QT_CONFIG(dialog)
         QDialog *dlg = qobject_cast<QDialog*>(window());
         if (dlg)
-            dlg->d_func()->setDefault(0);
+            dlg->d_func()->setDefault(nullptr);
         else
             d->defaultButton = false;
 #endif
diff --git a/src/widgets/widgets/qscrollarea.cpp b/src/widgets/widgets/qscrollarea.cpp
index 68aa545082..ce08e3439a 100644
--- a/src/widgets/widgets/qscrollarea.cpp
+++ b/src/widgets/widgets/qscrollarea.cpp
@@ -259,7 +259,7 @@ void QScrollArea::setWidget(QWidget *widget)
         return;
 
     delete d->widget;
-    d->widget = 0;
+    d->widget = nullptr;
     d->hbar->setValue(0);
     d->vbar->setValue(0);
     if (widget->parentWidget() != d->viewport)
@@ -285,9 +285,9 @@ QWidget *QScrollArea::takeWidget()
 {
     Q_D(QScrollArea);
     QWidget *w = d->widget;
-    d->widget = 0;
+    d->widget = nullptr;
     if (w)
-        w->setParent(0);
+        w->setParent(nullptr);
     return w;
 }
 
diff --git a/src/widgets/widgets/qscrollbar.cpp b/src/widgets/widgets/qscrollbar.cpp
index 08d771a27a..34ea017279 100644
--- a/src/widgets/widgets/qscrollbar.cpp
+++ b/src/widgets/widgets/qscrollbar.cpp
@@ -224,7 +224,7 @@ void QScrollBarPrivate::setTransient(bool value)
     if (transient != value) {
         transient = value;
         if (q->isVisible()) {
-            if (q->style()->styleHint(QStyle::SH_ScrollBar_Transient, 0, q))
+            if (q->style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, q))
                 q->update();
         } else if (!transient) {
             q->show();
@@ -235,7 +235,7 @@ void QScrollBarPrivate::setTransient(bool value)
 void QScrollBarPrivate::flash()
 {
     Q_Q(QScrollBar);
-    if (!flashed && q->style()->styleHint(QStyle::SH_ScrollBar_Transient, 0, q)) {
+    if (!flashed && q->style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, q)) {
         flashed = true;
         if (!q->isVisible())
             q->show();
@@ -319,7 +319,7 @@ void QScrollBar::initStyleOption(QStyleOptionSlider *option) const
     option->upsideDown = d->invertedAppearance;
     if (d->orientation == Qt::Horizontal)
         option->state |= QStyle::State_Horizontal;
-    if ((d->flashed || !d->transient) && style()->styleHint(QStyle::SH_ScrollBar_Transient, 0, this))
+    if ((d->flashed || !d->transient) && style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, this))
         option->state |= QStyle::State_On;
 }
 
@@ -376,7 +376,7 @@ void QScrollBarPrivate::init()
     invertedControls = true;
     pressedControl = hoverControl = QStyle::SC_None;
     pointerOutsidePressedControl = false;
-    transient = q->style()->styleHint(QStyle::SH_ScrollBar_Transient, 0, q);
+    transient = q->style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, q);
     flashed = false;
     flashTimer = 0;
     q->setFocusPolicy(Qt::NoFocus);
@@ -392,7 +392,7 @@ void QScrollBarPrivate::init()
 /*! \reimp */
 void QScrollBar::contextMenuEvent(QContextMenuEvent *event)
 {
-    if (!style()->styleHint(QStyle::SH_ScrollBar_ContextMenu, 0, this)) {
+    if (!style()->styleHint(QStyle::SH_ScrollBar_ContextMenu, nullptr, this)) {
         QAbstractSlider::contextMenuEvent(event);
         return ;
     }
@@ -412,7 +412,7 @@ void QScrollBar::contextMenuEvent(QContextMenuEvent *event)
     QAction *actScrollDn = menu->addAction(horiz ? tr("Scroll right") : tr("Scroll down"));
     QAction *actionSelected = menu->exec(event->globalPos());
     delete menu;
-    if (actionSelected == 0)
+    if (actionSelected == nullptr)
         /* do nothing */ ;
     else if (actionSelected == actScrollHere)
         setValue(d_func()->pixelPosToRangeValue(horiz ? event->pos().x() : event->pos().y()));
@@ -472,11 +472,11 @@ bool QScrollBar::event(QEvent *event)
             d_func()->updateHoverControl(he->pos());
         break;
     case QEvent::StyleChange:
-        d_func()->setTransient(style()->styleHint(QStyle::SH_ScrollBar_Transient, 0, this));
+        d_func()->setTransient(style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, this));
         break;
     case QEvent::Timer:
         if (static_cast<QTimerEvent *>(event)->timerId() == d->flashTimer) {
-            if (d->flashed && style()->styleHint(QStyle::SH_ScrollBar_Transient, 0, this)) {
+            if (d->flashed && style()->styleHint(QStyle::SH_ScrollBar_Transient, nullptr, this)) {
                 d->flashed = false;
                 update();
             }
@@ -545,7 +545,7 @@ void QScrollBar::mousePressEvent(QMouseEvent *e)
         d->stopRepeatAction();
 
     bool midButtonAbsPos = style()->styleHint(QStyle::SH_ScrollBar_MiddleClickAbsolutePosition,
-                                             0, this);
+                                             nullptr, this);
     QStyleOptionSlider opt;
     initStyleOption(&opt);
 
diff --git a/src/widgets/widgets/qsizegrip.cpp b/src/widgets/widgets/qsizegrip.cpp
index 662d4c9e92..2a4b4a0ad4 100644
--- a/src/widgets/widgets/qsizegrip.cpp
+++ b/src/widgets/widgets/qsizegrip.cpp
@@ -128,7 +128,7 @@ QSizeGripPrivate::QSizeGripPrivate()
     : dxMax(0)
     , dyMax(0)
     , gotMousePress(false)
-    , tlw(0)
+    , tlw(nullptr)
     , m_platformSizeGrip(false)
 {
 }
diff --git a/src/widgets/widgets/qsplashscreen.cpp b/src/widgets/widgets/qsplashscreen.cpp
index b7c3426e08..70f05033ea 100644
--- a/src/widgets/widgets/qsplashscreen.cpp
+++ b/src/widgets/widgets/qsplashscreen.cpp
@@ -137,7 +137,7 @@ public:
     perhaps Qt::WindowStaysOnTopHint.
 */
 QSplashScreen::QSplashScreen(const QPixmap &pixmap, Qt::WindowFlags f)
-    : QWidget(*(new QSplashScreenPrivate()), 0, Qt::SplashScreen | Qt::FramelessWindowHint | f)
+    : QWidget(*(new QSplashScreenPrivate()), nullptr, Qt::SplashScreen | Qt::FramelessWindowHint | f)
 {
     setPixmap(pixmap);  // Does an implicit repaint
 }
@@ -271,14 +271,14 @@ inline static bool waitForWindowExposed(QWindow *window, int timeout = 1000)
         if (remaining <= 0)
             break;
         QCoreApplication::processEvents(QEventLoop::AllEvents, remaining);
-        QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);
+        QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
 #if defined(Q_OS_WINRT)
         WaitForSingleObjectEx(GetCurrentThread(), TimeOutMs, false);
 #elif defined(Q_OS_WIN)
         Sleep(uint(TimeOutMs));
 #else
         struct timespec ts = { TimeOutMs / 1000, (TimeOutMs % 1000) * 1000 * 1000 };
-        nanosleep(&ts, NULL);
+        nanosleep(&ts, nullptr);
 #endif
     }
     return window->isExposed();
diff --git a/src/widgets/widgets/qsplitter.cpp b/src/widgets/widgets/qsplitter.cpp
index 1a5fb7f251..090aa5cc8b 100644
--- a/src/widgets/widgets/qsplitter.cpp
+++ b/src/widgets/widgets/qsplitter.cpp
@@ -1494,7 +1494,7 @@ int QSplitter::closestLegalPosition(int pos, int index)
 bool QSplitter::opaqueResize() const
 {
     Q_D(const QSplitter);
-    return d->opaqueResizeSet ? d->opaque : style()->styleHint(QStyle::SH_Splitter_OpaqueResize, 0, this);
+    return d->opaqueResizeSet ? d->opaque : style()->styleHint(QStyle::SH_Splitter_OpaqueResize, nullptr, this);
 }
 
 
@@ -1639,7 +1639,7 @@ int QSplitter::handleWidth() const
     if (d->handleWidth >= 0) {
         return d->handleWidth;
     } else {
-        return style()->pixelMetric(QStyle::PM_SplitterWidth, 0, this);
+        return style()->pixelMetric(QStyle::PM_SplitterWidth, nullptr, this);
     }
 }
 
diff --git a/src/widgets/widgets/qstackedwidget.cpp b/src/widgets/widgets/qstackedwidget.cpp
index f863964c58..a565d4ab4c 100644
--- a/src/widgets/widgets/qstackedwidget.cpp
+++ b/src/widgets/widgets/qstackedwidget.cpp
@@ -49,7 +49,7 @@ class QStackedWidgetPrivate : public QFramePrivate
 {
     Q_DECLARE_PUBLIC(QStackedWidget)
 public:
-    QStackedWidgetPrivate():layout(0){}
+    QStackedWidgetPrivate():layout(nullptr){}
     QStackedLayout *layout;
     bool blockChildAdd;
 };
diff --git a/src/widgets/widgets/qstatusbar.cpp b/src/widgets/widgets/qstatusbar.cpp
index 943b576ee3..4a1fef8b65 100644
--- a/src/widgets/widgets/qstatusbar.cpp
+++ b/src/widgets/widgets/qstatusbar.cpp
@@ -229,11 +229,11 @@ QStatusBar::QStatusBar(QWidget * parent)
     : QWidget(*new QStatusBarPrivate, parent, { })
 {
     Q_D(QStatusBar);
-    d->box = 0;
-    d->timer = 0;
+    d->box = nullptr;
+    d->timer = nullptr;
 
 #if QT_CONFIG(sizegrip)
-    d->resizer = 0;
+    d->resizer = nullptr;
     setSizeGripEnabled(true); // causes reformat()
 #else
     reformat();
@@ -451,7 +451,7 @@ void QStatusBar::setSizeGripEnabled(bool enabled)
             d->showSizeGrip = true;
         } else {
             delete d->resizer;
-            d->resizer = 0;
+            d->resizer = nullptr;
             d->showSizeGrip = false;
         }
         reformat();
@@ -497,7 +497,7 @@ void QStatusBar::reformat()
 
     int i;
     QStatusBarPrivate::SBItem* item;
-    for (i=0,item=0; i<d->items.size(); ++i) {
+    for (i=0,item=nullptr; i<d->items.size(); ++i) {
         item = d->items.at(i);
         if (!item || item->p)
             break;
@@ -508,7 +508,7 @@ void QStatusBar::reformat()
 
     l->addStretch(0);
 
-    for (item=0; i<d->items.size(); ++i) {
+    for (item=nullptr; i<d->items.size(); ++i) {
         item = d->items.at(i);
         if (!item)
             break;
@@ -556,7 +556,7 @@ void QStatusBar::showMessage(const QString &message, int timeout)
         d->timer->start(timeout);
     } else if (d->timer) {
         delete d->timer;
-        d->timer = 0;
+        d->timer = nullptr;
     }
     if (d->tempItem == message)
         return;
@@ -578,7 +578,7 @@ void QStatusBar::clearMessage()
         return;
     if (d->timer) {
         qDeleteInEventHandler(d->timer);
-        d->timer = 0;
+        d->timer = nullptr;
     }
     d->tempItem.clear();
     hideOrShow();
@@ -617,7 +617,7 @@ void QStatusBar::hideOrShow()
     Q_D(QStatusBar);
     bool haveMessage = !d->tempItem.isEmpty();
 
-    QStatusBarPrivate::SBItem* item = 0;
+    QStatusBarPrivate::SBItem* item = nullptr;
     for (int i=0; i<d->items.size(); ++i) {
         item = d->items.at(i);
         if (!item || item->p)
@@ -711,7 +711,7 @@ bool QStatusBar::event(QEvent *e)
         // Calculate new strut height and call reformat() if it has changed
         int maxH = fontMetrics().height();
 
-        QStatusBarPrivate::SBItem* item = 0;
+        QStatusBarPrivate::SBItem* item = nullptr;
         for (int i=0; i<d->items.size(); ++i) {
             item = d->items.at(i);
             if (!item)
@@ -731,7 +731,7 @@ bool QStatusBar::event(QEvent *e)
             update();
     }
     if (e->type() == QEvent::ChildRemoved) {
-        QStatusBarPrivate::SBItem* item = 0;
+        QStatusBarPrivate::SBItem* item = nullptr;
         for (int i=0; i<d->items.size(); ++i) {
             item = d->items.at(i);
             if (!item)
diff --git a/src/widgets/widgets/qtabbar.cpp b/src/widgets/widgets/qtabbar.cpp
index dfe362bdca..4e75cca704 100644
--- a/src/widgets/widgets/qtabbar.cpp
+++ b/src/widgets/widgets/qtabbar.cpp
@@ -76,7 +76,7 @@ class CloseButton : public QAbstractButton
     Q_OBJECT
 
 public:
-    explicit CloseButton(QWidget *parent = 0);
+    explicit CloseButton(QWidget *parent = nullptr);
 
     QSize sizeHint() const override;
     QSize minimumSizeHint() const override
@@ -424,18 +424,18 @@ void QTabBarPrivate::init()
     rightB->setAccessibleName(QTabBar::tr("Scroll Right"));
 #endif
     q->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);
-    elideMode = Qt::TextElideMode(q->style()->styleHint(QStyle::SH_TabBar_ElideMode, 0, q));
-    useScrollButtons = !q->style()->styleHint(QStyle::SH_TabBar_PreferNoArrows, 0, q);
+    elideMode = Qt::TextElideMode(q->style()->styleHint(QStyle::SH_TabBar_ElideMode, nullptr, q));
+    useScrollButtons = !q->style()->styleHint(QStyle::SH_TabBar_PreferNoArrows, nullptr, q);
 }
 
 QTabBarPrivate::Tab *QTabBarPrivate::at(int index)
 {
-    return validIndex(index)?&tabList[index]:0;
+    return validIndex(index)?&tabList[index]:nullptr;
 }
 
 const QTabBarPrivate::Tab *QTabBarPrivate::at(int index) const
 {
-    return validIndex(index)?&tabList[index]:0;
+    return validIndex(index)?&tabList[index]:nullptr;
 }
 
 int QTabBarPrivate::indexAtPos(const QPoint &p) const
@@ -460,7 +460,7 @@ void QTabBarPrivate::layoutTabs()
     bool vertTabs = verticalTabs(shape);
     int tabChainIndex = 0;
 
-    Qt::Alignment tabAlignment = Qt::Alignment(q->style()->styleHint(QStyle::SH_TabBar_Alignment, 0, q));
+    Qt::Alignment tabAlignment = Qt::Alignment(q->style()->styleHint(QStyle::SH_TabBar_Alignment, nullptr, q));
     QVector<QLayoutStruct> tabChain(tabList.count() + 2);
 
     // We put an empty item at the front and back and set its expansive attribute
@@ -787,7 +787,7 @@ void QTabBarPrivate::_q_closeTab()
     Q_Q(QTabBar);
     QObject *object = q->sender();
     int tabToClose = -1;
-    QTabBar::ButtonPosition closeSide = (QTabBar::ButtonPosition)q->style()->styleHint(QStyle::SH_TabBar_CloseButtonPosition, 0, q);
+    QTabBar::ButtonPosition closeSide = (QTabBar::ButtonPosition)q->style()->styleHint(QStyle::SH_TabBar_CloseButtonPosition, nullptr, q);
     for (int i = 0; i < tabList.count(); ++i) {
         if (closeSide == QTabBar::LeftSide) {
             if (tabList.at(i).leftWidget == object) {
@@ -984,7 +984,7 @@ int QTabBar::insertTab(int index, const QIcon& icon, const QString &text)
     if (d->closeButtonOnTabs) {
         QStyleOptionTab opt;
         initStyleOption(&opt, index);
-        ButtonPosition closeSide = (ButtonPosition)style()->styleHint(QStyle::SH_TabBar_CloseButtonPosition, 0, this);
+        ButtonPosition closeSide = (ButtonPosition)style()->styleHint(QStyle::SH_TabBar_CloseButtonPosition, nullptr, this);
         QAbstractButton *closeButton = new CloseButton(this);
         connect(closeButton, SIGNAL(clicked()), this, SLOT(_q_closeTab()));
         setTabButton(index, closeSide, closeButton);
@@ -1019,12 +1019,12 @@ void QTabBar::removeTab(int index)
         if (d->tabList[index].leftWidget) {
             d->tabList[index].leftWidget->hide();
             d->tabList[index].leftWidget->deleteLater();
-            d->tabList[index].leftWidget = 0;
+            d->tabList[index].leftWidget = nullptr;
         }
         if (d->tabList[index].rightWidget) {
             d->tabList[index].rightWidget->hide();
             d->tabList[index].rightWidget->deleteLater();
-            d->tabList[index].rightWidget = 0;
+            d->tabList[index].rightWidget = nullptr;
         }
 
         int newIndex = d->tabList[index].lastTab;
@@ -1395,7 +1395,7 @@ QSize QTabBar::iconSize() const
     Q_D(const QTabBar);
     if (d->iconSize.isValid())
         return d->iconSize;
-    int iconExtent = style()->pixelMetric(QStyle::PM_TabBarIconSize, 0, this);
+    int iconExtent = style()->pixelMetric(QStyle::PM_TabBarIconSize, nullptr, this);
     return QSize(iconExtent, iconExtent);
 
 }
@@ -1797,7 +1797,7 @@ void QTabBar::paintEvent(QPaintEvent *)
         if (!d->dragInProgress)
             p.drawControl(QStyle::CE_TabBarTab, tab);
         else {
-            int taboverlap = style()->pixelMetric(QStyle::PM_TabBarTabOverlap, 0, this);
+            int taboverlap = style()->pixelMetric(QStyle::PM_TabBarTabOverlap, nullptr, this);
             if (verticalTabs(d->shape))
                 d->movingTab->setGeometry(tab.rect.adjusted(0, -taboverlap, 0, taboverlap));
             else
@@ -2065,7 +2065,7 @@ void QTabBarPrivate::setupMovableTab()
     if (!movingTab)
         movingTab = new QMovableTabWidget(q);
 
-    int taboverlap = q->style()->pixelMetric(QStyle::PM_TabBarTabOverlap, 0 ,q);
+    int taboverlap = q->style()->pixelMetric(QStyle::PM_TabBarTabOverlap, nullptr ,q);
     QRect grabRect = q->tabRect(pressedIndex);
     if (verticalTabs(shape))
         grabRect.adjust(0, -taboverlap, 0, taboverlap);
@@ -2221,9 +2221,9 @@ void QTabBar::changeEvent(QEvent *event)
     switch (event->type()) {
     case QEvent::StyleChange:
         if (!d->elideModeSetByUser)
-            d->elideMode = Qt::TextElideMode(style()->styleHint(QStyle::SH_TabBar_ElideMode, 0, this));
+            d->elideMode = Qt::TextElideMode(style()->styleHint(QStyle::SH_TabBar_ElideMode, nullptr, this));
         if (!d->useScrollButtonsSetByUser)
-            d->useScrollButtons = !style()->styleHint(QStyle::SH_TabBar_PreferNoArrows, 0, this);
+            d->useScrollButtons = !style()->styleHint(QStyle::SH_TabBar_PreferNoArrows, nullptr, this);
         Q_FALLTHROUGH();
     case QEvent::FontChange:
         d->textSizes.clear();
@@ -2333,16 +2333,16 @@ void QTabBar::setTabsClosable(bool closable)
     if (d->closeButtonOnTabs == closable)
         return;
     d->closeButtonOnTabs = closable;
-    ButtonPosition closeSide = (ButtonPosition)style()->styleHint(QStyle::SH_TabBar_CloseButtonPosition, 0, this);
+    ButtonPosition closeSide = (ButtonPosition)style()->styleHint(QStyle::SH_TabBar_CloseButtonPosition, nullptr, this);
     if (!closable) {
         for (int i = 0; i < d->tabList.count(); ++i) {
             if (closeSide == LeftSide && d->tabList[i].leftWidget) {
                 d->tabList[i].leftWidget->deleteLater();
-                d->tabList[i].leftWidget = 0;
+                d->tabList[i].leftWidget = nullptr;
             }
             if (closeSide == RightSide && d->tabList[i].rightWidget) {
                 d->tabList[i].rightWidget->deleteLater();
-                d->tabList[i].rightWidget = 0;
+                d->tabList[i].rightWidget = nullptr;
             }
         }
     } else {
@@ -2637,8 +2637,8 @@ CloseButton::CloseButton(QWidget *parent)
 QSize CloseButton::sizeHint() const
 {
     ensurePolished();
-    int width = style()->pixelMetric(QStyle::PM_TabCloseIndicatorWidth, 0, this);
-    int height = style()->pixelMetric(QStyle::PM_TabCloseIndicatorHeight, 0, this);
+    int width = style()->pixelMetric(QStyle::PM_TabCloseIndicatorWidth, nullptr, this);
+    int height = style()->pixelMetric(QStyle::PM_TabCloseIndicatorHeight, nullptr, this);
     return QSize(width, height);
 }
 
@@ -2671,7 +2671,7 @@ void CloseButton::paintEvent(QPaintEvent *)
 
     if (const QTabBar *tb = qobject_cast<const QTabBar *>(parent())) {
         int index = tb->currentIndex();
-        QTabBar::ButtonPosition position = (QTabBar::ButtonPosition)style()->styleHint(QStyle::SH_TabBar_CloseButtonPosition, 0, tb);
+        QTabBar::ButtonPosition position = (QTabBar::ButtonPosition)style()->styleHint(QStyle::SH_TabBar_CloseButtonPosition, nullptr, tb);
         if (tb->tabButton(index, position) == this)
             opt.state |= QStyle::State_Selected;
     }
diff --git a/src/widgets/widgets/qtabbar_p.h b/src/widgets/widgets/qtabbar_p.h
index 5552c43548..6f77579108 100644
--- a/src/widgets/widgets/qtabbar_p.h
+++ b/src/widgets/widgets/qtabbar_p.h
@@ -105,9 +105,9 @@ public:
     struct Tab {
         inline Tab(const QIcon &ico, const QString &txt)
             : enabled(true) , shortcutId(0), text(txt), icon(ico),
-            leftWidget(0), rightWidget(0), lastTab(-1), dragOffset(0)
+            leftWidget(nullptr), rightWidget(nullptr), lastTab(-1), dragOffset(0)
 #if QT_CONFIG(animation)
-            , animation(0)
+            , animation(nullptr)
 #endif // animation
         {}
         bool operator==(const Tab &other) const { return &other == this; }
diff --git a/src/widgets/widgets/qtabwidget.cpp b/src/widgets/widgets/qtabwidget.cpp
index 2b3b8280bb..28c91a89e7 100644
--- a/src/widgets/widgets/qtabwidget.cpp
+++ b/src/widgets/widgets/qtabwidget.cpp
@@ -215,9 +215,9 @@ public:
 };
 
 QTabWidgetPrivate::QTabWidgetPrivate()
-    : tabs(0), stack(0), dirty(true),
+    : tabs(nullptr), stack(nullptr), dirty(true),
       pos(QTabWidget::North), shape(QTabWidget::Rounded),
-      leftCornerWidget(0), rightCornerWidget(0)
+      leftCornerWidget(nullptr), rightCornerWidget(nullptr)
 {}
 
 QTabWidgetPrivate::~QTabWidgetPrivate()
@@ -249,7 +249,7 @@ void QTabWidgetPrivate::init()
     q->setFocusPolicy(Qt::TabFocus);
     q->setFocusProxy(tabs);
     q->setTabPosition(static_cast<QTabWidget::TabPosition> (q->style()->styleHint(
-                      QStyle::SH_TabWidget_DefaultTabPosition, 0, q )));
+                      QStyle::SH_TabWidget_DefaultTabPosition, nullptr, q )));
 
 }
 
@@ -280,7 +280,7 @@ void QTabWidgetPrivate::initBasicStyleOption(QStyleOptionTabWidgetFrame *option)
     if (q->documentMode())
         option->lineWidth = 0;
     else
-        option->lineWidth = q->style()->pixelMetric(QStyle::PM_DefaultFrameWidth, 0, q);
+        option->lineWidth = q->style()->pixelMetric(QStyle::PM_DefaultFrameWidth, nullptr, q);
 
     switch (pos) {
     case QTabWidget::North:
@@ -319,7 +319,7 @@ void QTabWidget::initStyleOption(QStyleOptionTabWidgetFrame *option) const
     Q_D(const QTabWidget);
     d->initBasicStyleOption(option);
 
-    int exth = style()->pixelMetric(QStyle::PM_TabBarBaseHeight, 0, this);
+    int exth = style()->pixelMetric(QStyle::PM_TabBarBaseHeight, nullptr, this);
     QSize t(0, d->stack->frameWidth());
     if (d->tabs->isVisibleTo(const_cast<QTabWidget *>(this))) {
         t = d->tabs->sizeHint();
diff --git a/src/widgets/widgets/qtextedit.cpp b/src/widgets/widgets/qtextedit.cpp
index dd2ea3f18f..10de7d0b9e 100644
--- a/src/widgets/widgets/qtextedit.cpp
+++ b/src/widgets/widgets/qtextedit.cpp
@@ -117,7 +117,7 @@ public:
 };
 
 QTextEditPrivate::QTextEditPrivate()
-    : control(0),
+    : control(nullptr),
       autoFormatting(QTextEdit::AutoNone), tabChangesFocus(false),
       lineWrap(QTextEdit::WidgetWidth), lineWrapColumnOrWidth(0),
       wordWrap(QTextOption::WrapAtWordBoundaryOrAnywhere), clickCausedFocus(0),
diff --git a/src/widgets/widgets/qtoolbar.cpp b/src/widgets/widgets/qtoolbar.cpp
index 79182dfa33..b4e90c7d71 100644
--- a/src/widgets/widgets/qtoolbar.cpp
+++ b/src/widgets/widgets/qtoolbar.cpp
@@ -91,7 +91,7 @@ void QToolBarPrivate::init()
     q->setAttribute(Qt::WA_X11NetWmWindowTypeToolBar);
 
     QStyle *style = q->style();
-    int e = style->pixelMetric(QStyle::PM_ToolBarIconSize, 0, q);
+    int e = style->pixelMetric(QStyle::PM_ToolBarIconSize, nullptr, q);
     iconSize = QSize(e, e);
 
     layout = new QToolBarLayout(q);
@@ -99,7 +99,7 @@ void QToolBarPrivate::init()
 
     toggleViewAction = new QAction(q);
     toggleViewAction->setCheckable(true);
-    q->setMovable(q->style()->styleHint(QStyle::SH_ToolBar_Movable, 0, q ));
+    q->setMovable(q->style()->styleHint(QStyle::SH_ToolBar_Movable, nullptr, q ));
     QObject::connect(toggleViewAction, SIGNAL(triggered(bool)), q, SLOT(_q_toggleView(bool)));
 }
 
@@ -173,21 +173,21 @@ void QToolBarPrivate::initDrag(const QPoint &pos)
 {
     Q_Q(QToolBar);
 
-    if (state != 0)
+    if (state != nullptr)
         return;
 
     QMainWindow *win = qobject_cast<QMainWindow*>(parent);
-    Q_ASSERT(win != 0);
+    Q_ASSERT(win != nullptr);
     QMainWindowLayout *layout = qt_mainwindow_layout(win);
-    Q_ASSERT(layout != 0);
-    if (layout->pluggingWidget != 0) // the main window is animating a docking operation
+    Q_ASSERT(layout != nullptr);
+    if (layout->pluggingWidget != nullptr) // the main window is animating a docking operation
         return;
 
     state = new DragState;
     state->pressPos = pos;
     state->dragging = false;
     state->moving = false;
-    state->widgetItem = 0;
+    state->widgetItem = nullptr;
 
     if (q->isRightToLeft())
         state->pressPos = QPoint(q->width() - state->pressPos.x(), state->pressPos.y());
@@ -197,19 +197,19 @@ void QToolBarPrivate::startDrag(bool moving)
 {
     Q_Q(QToolBar);
 
-    Q_ASSERT(state != 0);
+    Q_ASSERT(state != nullptr);
 
     if ((moving && state->moving) || state->dragging)
         return;
 
     QMainWindow *win = qobject_cast<QMainWindow*>(parent);
-    Q_ASSERT(win != 0);
+    Q_ASSERT(win != nullptr);
     QMainWindowLayout *layout = qt_mainwindow_layout(win);
-    Q_ASSERT(layout != 0);
+    Q_ASSERT(layout != nullptr);
 
     if (!moving) {
         state->widgetItem = layout->unplug(q);
-        Q_ASSERT(state->widgetItem != 0);
+        Q_ASSERT(state->widgetItem != nullptr);
     }
     state->dragging = !moving;
     state->moving = moving;
@@ -218,13 +218,13 @@ void QToolBarPrivate::startDrag(bool moving)
 void QToolBarPrivate::endDrag()
 {
     Q_Q(QToolBar);
-    Q_ASSERT(state != 0);
+    Q_ASSERT(state != nullptr);
 
     q->releaseMouse();
 
     if (state->dragging) {
         QMainWindowLayout *layout = qt_mainwindow_layout(qobject_cast<QMainWindow *>(q->parentWidget()));
-        Q_ASSERT(layout != 0);
+        Q_ASSERT(layout != nullptr);
 
         if (!layout->plug(state->widgetItem)) {
             if (q->isFloatable()) {
@@ -239,7 +239,7 @@ void QToolBarPrivate::endDrag()
     }
 
     delete state;
-    state = 0;
+    state = nullptr;
 }
 
 bool QToolBarPrivate::mousePressEvent(QMouseEvent *event)
@@ -278,7 +278,7 @@ bool QToolBarPrivate::mousePressEvent(QMouseEvent *event)
 
 bool QToolBarPrivate::mouseReleaseEvent(QMouseEvent*)
 {
-    if (state != 0) {
+    if (state != nullptr) {
         endDrag();
         return true;
     } else {
@@ -310,13 +310,13 @@ bool QToolBarPrivate::mouseMoveEvent(QMouseEvent *event)
     }
 
     QMainWindow *win = qobject_cast<QMainWindow*>(parent);
-    if (win == 0)
+    if (win == nullptr)
         return true;
 
     QMainWindowLayout *layout = qt_mainwindow_layout(win);
-    Q_ASSERT(layout != 0);
+    Q_ASSERT(layout != nullptr);
 
-    if (layout->pluggingWidget == 0
+    if (layout->pluggingWidget == nullptr
         && (event->pos() - state->pressPos).manhattanLength() > QApplication::startDragDistance()) {
             const bool wasDragging = state->dragging;
             const bool moving = !q->isWindow() && (orientation == Qt::Vertical ?
@@ -673,16 +673,16 @@ void QToolBar::setIconSize(const QSize &iconSize)
         if (mw && mw->layout()) {
             QLayout *layout = mw->layout();
             int i = 0;
-            QLayoutItem *item = 0;
+            QLayoutItem *item = nullptr;
             do {
                 item = layout->itemAt(i++);
                 if (item && (item->widget() == this))
                     sz = mw->iconSize();
-            } while (!sz.isValid() && item != 0);
+            } while (!sz.isValid() && item != nullptr);
         }
     }
     if (!sz.isValid()) {
-        const int metric = style()->pixelMetric(QStyle::PM_ToolBarIconSize, 0, this);
+        const int metric = style()->pixelMetric(QStyle::PM_ToolBarIconSize, nullptr, this);
         sz = QSize(metric, metric);
     }
     if (d->iconSize != sz) {
@@ -945,7 +945,7 @@ QAction *QToolBar::actionAt(const QPoint &p) const
     QWidget *widget = childAt(p);
     int index = d->layout->indexOf(widget);
     if (index == -1)
-        return 0;
+        return nullptr;
     QLayoutItem *item = d->layout->itemAt(index);
     return static_cast<QToolBarItem*>(item)->action;
 }
@@ -966,7 +966,7 @@ void QToolBar::actionEvent(QActionEvent *event)
 
     switch (event->type()) {
         case QEvent::ActionAdded: {
-            Q_ASSERT_X(widgetAction == 0 || d->layout->indexOf(widgetAction) == -1,
+            Q_ASSERT_X(widgetAction == nullptr || d->layout->indexOf(widgetAction) == -1,
                         "QToolBar", "widgets cannot be inserted multiple times");
 
             // reparent the action to this toolbar if it has been created
@@ -974,7 +974,7 @@ void QToolBar::actionEvent(QActionEvent *event)
             // preserve Qt 4.1.x behavior. The widget is already
             // reparented to us due to the createWidget call inside
             // createItem()
-            if (widgetAction != 0 && widgetAction->d_func()->autoCreated)
+            if (widgetAction != nullptr && widgetAction->d_func()->autoCreated)
                 widgetAction->setParent(this);
 
             int index = d->layout->count();
@@ -1059,18 +1059,18 @@ void QToolBar::paintEvent(QPaintEvent *)
 */
 static bool waitForPopup(QToolBar *tb, QWidget *popup)
 {
-    if (popup == 0 || popup->isHidden())
+    if (popup == nullptr || popup->isHidden())
         return false;
 
     QWidget *w = popup;
-    while (w != 0) {
+    while (w != nullptr) {
         if (w == tb)
             return true;
         w = w->parentWidget();
     }
 
     QMenu *menu = qobject_cast<QMenu*>(popup);
-    if (menu == 0)
+    if (menu == nullptr)
         return false;
 
     QAction *action = menu->menuAction();
@@ -1161,7 +1161,7 @@ bool QToolBar::event(QEvent *event)
             return true;
         break;
     case QEvent::Leave:
-        if (d->state != 0 && d->state->dragging) {
+        if (d->state != nullptr && d->state->dragging) {
 #ifdef Q_OS_WIN
             // This is a workaround for loosing the mouse on Vista.
             QPoint pos = QCursor::pos();
@@ -1213,7 +1213,7 @@ QWidget *QToolBar::widgetForAction(QAction *action) const
 
     int index = d->layout->indexOf(action);
     if (index == -1)
-        return 0;
+        return nullptr;
 
     return d->layout->itemAt(index)->widget();
 }
@@ -1233,7 +1233,7 @@ void QToolBar::initStyleOption(QStyleOptionToolBar *option) const
     option->initFrom(this);
     if (orientation() == Qt::Horizontal)
         option->state |= QStyle::State_Horizontal;
-    option->lineWidth = style()->pixelMetric(QStyle::PM_ToolBarFrameWidth, 0, this);
+    option->lineWidth = style()->pixelMetric(QStyle::PM_ToolBarFrameWidth, nullptr, this);
     option->features = d->layout->movable()
                         ? QStyleOptionToolBar::Movable
                         : QStyleOptionToolBar::None;
@@ -1247,7 +1247,7 @@ void QToolBar::initStyleOption(QStyleOptionToolBar *option) const
         return;
 
     QMainWindowLayout *layout = qt_mainwindow_layout(mainWindow);
-    Q_ASSERT_X(layout != 0, "QToolBar::initStyleOption()",
+    Q_ASSERT_X(layout != nullptr, "QToolBar::initStyleOption()",
                "QMainWindow->layout() != QMainWindowLayout");
 
     layout->getStyleOptionInfo(option, const_cast<QToolBar *>(this));
diff --git a/src/widgets/widgets/qtoolbararealayout.cpp b/src/widgets/widgets/qtoolbararealayout.cpp
index adc329131c..493c094cc1 100644
--- a/src/widgets/widgets/qtoolbararealayout.cpp
+++ b/src/widgets/widgets/qtoolbararealayout.cpp
@@ -91,7 +91,7 @@ bool QToolBarAreaLayoutItem::skip() const
 {
     if (gap)
         return false;
-    return widgetItem == 0 || widgetItem->isEmpty();
+    return widgetItem == nullptr || widgetItem->isEmpty();
 }
 
 /******************************************************************************
@@ -302,7 +302,7 @@ QLayoutItem *QToolBarAreaLayoutInfo::insertToolBar(QToolBar *before, QToolBar *t
 
 void QToolBarAreaLayoutInfo::insertItem(QToolBar *before, QLayoutItem *item)
 {
-    if (before == 0) {
+    if (before == nullptr) {
         if (lines.isEmpty())
             lines.append(QToolBarAreaLayoutLine(o));
         lines.last().toolBarItems.append(item);
@@ -330,7 +330,7 @@ void QToolBarAreaLayoutInfo::removeToolBar(QToolBar *toolBar)
             QToolBarAreaLayoutItem &item = line.toolBarItems[k];
             if (item.widgetItem->widget() == toolBar) {
                 delete item.widgetItem;
-                item.widgetItem = 0;
+                item.widgetItem = nullptr;
                 line.toolBarItems.removeAt(k);
 
                 if (line.toolBarItems.isEmpty() && j < lines.count() - 1)
@@ -344,7 +344,7 @@ void QToolBarAreaLayoutInfo::removeToolBar(QToolBar *toolBar)
 
 void QToolBarAreaLayoutInfo::insertToolBarBreak(QToolBar *before)
 {
-    if (before == 0) {
+    if (before == nullptr) {
         if (!lines.isEmpty() && lines.constLast().toolBarItems.isEmpty())
             return;
         lines.append(QToolBarAreaLayoutLine(o));
@@ -729,7 +729,7 @@ QRect QToolBarAreaLayout::rectHint(const QRect &r) const
 
 QLayoutItem *QToolBarAreaLayout::itemAt(int *x, int index) const
 {
-    Q_ASSERT(x != 0);
+    Q_ASSERT(x != nullptr);
 
     for (int i = 0; i < QInternal::DockCount; ++i) {
         const QToolBarAreaLayoutInfo &dock = docks[i];
@@ -744,12 +744,12 @@ QLayoutItem *QToolBarAreaLayout::itemAt(int *x, int index) const
         }
     }
 
-    return 0;
+    return nullptr;
 }
 
 QLayoutItem *QToolBarAreaLayout::takeAt(int *x, int index)
 {
-    Q_ASSERT(x != 0);
+    Q_ASSERT(x != nullptr);
 
     for (int i = 0; i < QInternal::DockCount; ++i) {
         QToolBarAreaLayoutInfo &dock = docks[i];
@@ -768,7 +768,7 @@ QLayoutItem *QToolBarAreaLayout::takeAt(int *x, int index)
         }
     }
 
-    return 0;
+    return nullptr;
 }
 
 void QToolBarAreaLayout::deleteAllLayoutItems()
@@ -783,7 +783,7 @@ void QToolBarAreaLayout::deleteAllLayoutItems()
                 QToolBarAreaLayoutItem &item = line.toolBarItems[k];
                 if (!item.gap)
                     delete item.widgetItem;
-                item.widgetItem = 0;
+                item.widgetItem = nullptr;
             }
         }
     }
@@ -811,7 +811,7 @@ QLayoutItem *QToolBarAreaLayout::insertToolBar(QToolBar *before, QToolBar *toolB
 {
     QInternal::DockPosition pos = findToolBar(before);
     if (pos == QInternal::DockCount)
-        return 0;
+        return nullptr;
 
     return docks[pos].insertToolBar(before, toolBar);
 }
@@ -826,7 +826,7 @@ void QToolBarAreaLayout::removeToolBar(QToolBar *toolBar)
 
 QLayoutItem *QToolBarAreaLayout::addToolBar(QInternal::DockPosition pos, QToolBar *toolBar)
 {
-    return docks[pos].insertToolBar(0, toolBar);
+    return docks[pos].insertToolBar(nullptr, toolBar);
 }
 
 void QToolBarAreaLayout::insertToolBarBreak(QToolBar *before)
@@ -847,7 +847,7 @@ void QToolBarAreaLayout::removeToolBarBreak(QToolBar *before)
 
 void QToolBarAreaLayout::addToolBarBreak(QInternal::DockPosition pos)
 {
-    docks[pos].insertToolBarBreak(0);
+    docks[pos].insertToolBarBreak(nullptr);
 }
 
 void QToolBarAreaLayout::moveToolBar(QToolBar *toolbar, int p)
@@ -878,7 +878,7 @@ void QToolBarAreaLayout::insertItem(QToolBar *before, QLayoutItem *item)
 void QToolBarAreaLayout::apply(bool animate)
 {
     QMainWindowLayout *layout = qt_mainwindow_layout(mainWindow);
-    Q_ASSERT(layout != 0);
+    Q_ASSERT(layout != nullptr);
 
     Qt::LayoutDirection dir = mainWindow->layoutDirection();
 
@@ -1117,13 +1117,13 @@ QToolBarAreaLayoutItem *QToolBarAreaLayout::item(const QList<int> &path)
     Q_ASSERT(path.count() == 3);
 
     if (path.at(0) < 0 || path.at(0) >= QInternal::DockCount)
-        return 0;
+        return nullptr;
     QToolBarAreaLayoutInfo &info = docks[path.at(0)];
     if (path.at(1) < 0 || path.at(1) >= info.lines.count())
-        return 0;
+        return nullptr;
     QToolBarAreaLayoutLine &line = info.lines[path.at(1)];
     if (path.at(2) < 0 || path.at(2) >= line.toolBarItems.count())
-        return 0;
+        return nullptr;
     return &(line.toolBarItems[path.at(2)]);
 }
 
@@ -1143,10 +1143,10 @@ QLayoutItem *QToolBarAreaLayout::plug(const QList<int> &path)
     QToolBarAreaLayoutItem *item = this->item(path);
     if (Q_UNLIKELY(!item)) {
         qWarning() << "No item at" << path;
-        return 0;
+        return nullptr;
     }
     Q_ASSERT(item->gap);
-    Q_ASSERT(item->widgetItem != 0);
+    Q_ASSERT(item->widgetItem != nullptr);
     item->gap = false;
     return item->widgetItem;
 }
@@ -1352,14 +1352,14 @@ bool QToolBarAreaLayout::restoreState(QDataStream &stream, const QList<QToolBar*
                 rect = unpackRect(geom0, geom1, &floating);
             }
 
-            QToolBar *toolBar = 0;
+            QToolBar *toolBar = nullptr;
             for (int x = 0; x < toolBars.count(); ++x) {
                 if (toolBars.at(x)->objectName() == objectName) {
                     toolBar = toolBars.takeAt(x);
                     break;
                 }
             }
-            if (toolBar == 0) {
+            if (toolBar == nullptr) {
                 continue;
             }
 
diff --git a/src/widgets/widgets/qtoolbarlayout.cpp b/src/widgets/widgets/qtoolbarlayout.cpp
index ec60309806..89c7f32b28 100644
--- a/src/widgets/widgets/qtoolbarlayout.cpp
+++ b/src/widgets/widgets/qtoolbarlayout.cpp
@@ -69,13 +69,13 @@ extern QMainWindowLayout *qt_mainwindow_layout(const QMainWindow *window);
 */
 
 QToolBarItem::QToolBarItem(QWidget *widget)
-    : QWidgetItem(widget), action(0), customWidget(false)
+    : QWidgetItem(widget), action(nullptr), customWidget(false)
 {
 }
 
 bool QToolBarItem::isEmpty() const
 {
-    return action == 0 || !action->isVisible();
+    return action == nullptr || !action->isVisible();
 }
 
 /******************************************************************************
@@ -84,7 +84,7 @@ bool QToolBarItem::isEmpty() const
 
 QToolBarLayout::QToolBarLayout(QWidget *parent)
     : QLayout(parent), expanded(false), animating(false), dirty(true),
-        expanding(false), empty(true), expandFlag(false), popupMenu(0)
+        expanding(false), empty(true), expandFlag(false), popupMenu(nullptr)
 {
     QToolBar *tb = qobject_cast<QToolBar*>(parent);
     if (!tb)
@@ -132,15 +132,15 @@ bool QToolBarLayout::hasExpandFlag() const
 
 void QToolBarLayout::setUsePopupMenu(bool set)
 {
-    if (!dirty && ((popupMenu == 0) == set))
+    if (!dirty && ((popupMenu == nullptr) == set))
         invalidate();
     if (!set) {
         QObject::connect(extension, SIGNAL(clicked(bool)),
                         this, SLOT(setExpanded(bool)), Qt::UniqueConnection);
         extension->setPopupMode(QToolButton::DelayedPopup);
-        extension->setMenu(0);
+        extension->setMenu(nullptr);
         delete popupMenu;
-        popupMenu = 0;
+        popupMenu = nullptr;
     } else {
         QObject::disconnect(extension, SIGNAL(clicked(bool)),
                             this, SLOT(setExpanded(bool)));
@@ -169,21 +169,21 @@ void QToolBarLayout::addItem(QLayoutItem*)
 QLayoutItem *QToolBarLayout::itemAt(int index) const
 {
     if (index < 0 || index >= items.count())
-        return 0;
+        return nullptr;
     return items.at(index);
 }
 
 QLayoutItem *QToolBarLayout::takeAt(int index)
 {
     if (index < 0 || index >= items.count())
-        return 0;
+        return nullptr;
     QToolBarItem *item = items.takeAt(index);
 
     if (popupMenu)
         popupMenu->removeAction(item->action);
 
     QWidgetAction *widgetAction = qobject_cast<QWidgetAction*>(item->action);
-    if (widgetAction != 0 && item->customWidget) {
+    if (widgetAction != nullptr && item->customWidget) {
         widgetAction->releaseWidget(item->widget());
     } else {
         // destroy the QToolButton/QToolBarSeparator
@@ -251,7 +251,7 @@ bool QToolBarLayout::movable() const
     if (!tb)
         return false;
     QMainWindow *win = qobject_cast<QMainWindow*>(tb->parentWidget());
-    return tb->isMovable() && win != 0;
+    return tb->isMovable() && win != nullptr;
 }
 
 void QToolBarLayout::updateGeomArray() const
@@ -343,7 +343,7 @@ void QToolBarLayout::updateGeomArray() const
 static bool defaultWidgetAction(QToolBarItem *item)
 {
     QWidgetAction *a = qobject_cast<QWidgetAction*>(item->action);
-    return a != 0 && a->defaultWidget() == item->widget();
+    return a != nullptr && a->defaultWidget() == item->widget();
 }
 
 void QToolBarLayout::updateMacBorderMetrics()
@@ -568,7 +568,7 @@ bool QToolBarLayout::layoutActions(const QSize &size)
     // widgets into the menu. If only custom widget actions are chopped off, the popup menu
     // is empty. So we show the little extension button to show something is chopped off,
     // but we make it disabled.
-    extension->setEnabled(popupMenu == 0 || !extensionMenuContainsOnlyWidgetActions);
+    extension->setEnabled(popupMenu == nullptr || !extensionMenuContainsOnlyWidgetActions);
 
     // we have to do the show/hide here, because it triggers more calls to setGeometry :(
     for (int i = 0; i < showWidgets.count(); ++i)
@@ -615,7 +615,7 @@ QSize QToolBarLayout::expandedSize(const QSize &size) const
         ++rows;      // we want to expand to at least two rows
     int space = total_w/rows + spacing + extensionExtent;
     space = qMax(space, min_w - pick(o, margins) - handleExtent);
-    if (win != 0)
+    if (win != nullptr)
         space = qMin(space, pick(o, win->size()) - pick(o, margins) - handleExtent);
 
     int w = 0;
@@ -651,7 +651,7 @@ QSize QToolBarLayout::expandedSize(const QSize &size) const
 
     w += pick(Qt::Horizontal, margins) + handleExtent + spacing + extensionExtent;
     w = qMax(w, min_w);
-    if (win != 0)
+    if (win != nullptr)
         w = qMin(w, pick(o, win->size()));
     h += pick(Qt::Vertical, margins) - spacing; //there is no spacing before the first row
 
@@ -710,14 +710,14 @@ QToolBarItem *QToolBarLayout::createItem(QAction *action)
 {
     bool customWidget = false;
     bool standardButtonWidget = false;
-    QWidget *widget = 0;
+    QWidget *widget = nullptr;
     QToolBar *tb = qobject_cast<QToolBar*>(parentWidget());
     if (!tb)
-        return (QToolBarItem *)0;
+        return (QToolBarItem *)nullptr;
 
     if (QWidgetAction *widgetAction = qobject_cast<QWidgetAction *>(action)) {
         widget = widgetAction->requestWidget(tb);
-        if (widget != 0) {
+        if (widget != nullptr) {
             widget->setAttribute(Qt::WA_LayoutUsesWidgetRect);
             customWidget = true;
         }
diff --git a/src/widgets/widgets/qtoolbox.cpp b/src/widgets/widgets/qtoolbox.cpp
index 4d7f543a99..4767394842 100644
--- a/src/widgets/widgets/qtoolbox.cpp
+++ b/src/widgets/widgets/qtoolbox.cpp
@@ -111,7 +111,7 @@ public:
     typedef std::vector<std::unique_ptr<Page>> PageList;
 
     inline QToolBoxPrivate()
-        : currentPage(0)
+        : currentPage(nullptr)
     {
     }
     void _q_buttonClicked();
@@ -157,7 +157,7 @@ const QToolBoxPrivate::Page *QToolBoxPrivate::page(int index) const
 
 void QToolBoxPrivate::updateTabs()
 {
-    QToolBoxButton *lastButton = currentPage ? currentPage->button : 0;
+    QToolBoxButton *lastButton = currentPage ? currentPage->button : nullptr;
     bool after = false;
     int index = 0;
     for (const auto &page : pageList) {
@@ -184,7 +184,7 @@ QSize QToolBoxButton::sizeHint() const
 {
     QSize iconSize(8, 8);
     if (!icon().isNull()) {
-        int icone = style()->pixelMetric(QStyle::PM_SmallIconSize, 0, parentWidget() /* QToolBox */);
+        int icone = style()->pixelMetric(QStyle::PM_SmallIconSize, nullptr, parentWidget() /* QToolBox */);
         iconSize += QSize(icone + 2, icone);
     }
     QSize textSize = fontMetrics().size(Qt::TextShowMnemonic, text()) + QSize(0, 8);
@@ -197,7 +197,7 @@ QSize QToolBoxButton::minimumSizeHint() const
 {
     if (icon().isNull())
         return QSize();
-    int icone = style()->pixelMetric(QStyle::PM_SmallIconSize, 0, parentWidget() /* QToolBox */);
+    int icone = style()->pixelMetric(QStyle::PM_SmallIconSize, nullptr, parentWidget() /* QToolBox */);
     return QSize(icone + 8, icone + 8);
 }
 
@@ -378,7 +378,7 @@ int QToolBox::insertItem(int index, QWidget *widget, const QIcon &icon, const QS
             QWidget *current = d->currentPage->widget;
             int oldindex = indexOf(current);
             if (index <= oldindex) {
-                d->currentPage = 0; // trigger change
+                d->currentPage = nullptr; // trigger change
                 setCurrentIndex(oldindex);
             }
         }
@@ -472,10 +472,10 @@ void QToolBoxPrivate::_q_widgetDestroyed(QObject *object)
     pageList.erase(std::remove_if(pageList.begin(), pageList.end(), pageEquals(c)), pageList.end());
 
     if (pageList.empty()) {
-        currentPage = 0;
+        currentPage = nullptr;
         emit q->currentChanged(-1);
     } else if (removeCurrent) {
-        currentPage = 0;
+        currentPage = nullptr;
         q->setCurrentIndex(0);
     }
 }
@@ -562,7 +562,7 @@ QWidget *QToolBox::widget(int index) const
 int QToolBox::indexOf(QWidget *widget) const
 {
     Q_D(const QToolBox);
-    const QToolBoxPrivate::Page *c = (widget ? d->page(widget) : 0);
+    const QToolBoxPrivate::Page *c = (widget ? d->page(widget) : nullptr);
     if (!c)
         return -1;
     const auto it = std::find_if(d->pageList.cbegin(), d->pageList.cend(), pageEquals(c));
diff --git a/src/widgets/widgets/qtoolbutton.cpp b/src/widgets/widgets/qtoolbutton.cpp
index b00b219386..263fe5d8ce 100644
--- a/src/widgets/widgets/qtoolbutton.cpp
+++ b/src/widgets/widgets/qtoolbutton.cpp
@@ -202,7 +202,7 @@ QToolButton::QToolButton(QWidget * parent)
 void QToolButtonPrivate::init()
 {
     Q_Q(QToolButton);
-    defaultAction = 0;
+    defaultAction = nullptr;
 #if QT_CONFIG(toolbar)
     if (qobject_cast<QToolBar*>(parent))
         autoRaise = true;
@@ -227,7 +227,7 @@ void QToolButtonPrivate::init()
 #endif
 
     setLayoutItemMargins(QStyle::SE_ToolButtonLayoutItem);
-    delay = q->style()->styleHint(QStyle::SH_ToolButton_PopupDelay, 0, q);
+    delay = q->style()->styleHint(QStyle::SH_ToolButton_PopupDelay, nullptr, q);
 }
 
 /*!
@@ -477,10 +477,10 @@ void QToolButton::actionEvent(QActionEvent *event)
         break;
     case QEvent::ActionRemoved:
         if (d->defaultAction == action)
-            d->defaultAction = 0;
+            d->defaultAction = nullptr;
 #if QT_CONFIG(menu)
         if (action == d->menuAction)
-            d->menuAction = 0;
+            d->menuAction = nullptr;
 #endif
         action->disconnect(this);
         break;
@@ -583,7 +583,7 @@ void QToolButton::changeEvent(QEvent *e)
                || e->type() == QEvent::MacSizeChange
 #endif
                ) {
-        d->delay = style()->styleHint(QStyle::SH_ToolButton_PopupDelay, 0, this);
+        d->delay = style()->styleHint(QStyle::SH_ToolButton_PopupDelay, nullptr, this);
         d->setLayoutItemMargins(QStyle::SE_ToolButtonLayoutItem);
     }
 #endif
@@ -649,7 +649,7 @@ void QToolButton::setMenu(QMenu* menu)
 {
     Q_D(QToolButton);
 
-    if (d->menuAction == (menu ? menu->menuAction() : 0))
+    if (d->menuAction == (menu ? menu->menuAction() : nullptr))
         return;
 
     if (d->menuAction)
@@ -659,7 +659,7 @@ void QToolButton::setMenu(QMenu* menu)
         d->menuAction = menu->menuAction();
         addAction(d->menuAction);
     } else {
-        d->menuAction = 0;
+        d->menuAction = nullptr;
     }
 
     // changing the menu set may change the size hint, so reset it
diff --git a/src/widgets/widgets/qwidgetanimator.cpp b/src/widgets/widgets/qwidgetanimator.cpp
index 486d65d92c..cec6ba1dea 100644
--- a/src/widgets/widgets/qwidgetanimator.cpp
+++ b/src/widgets/widgets/qwidgetanimator.cpp
@@ -99,7 +99,7 @@ void QWidgetAnimator::animate(QWidget *widget, const QRect &_final_geometry, boo
 
 #if QT_CONFIG(animation)
     //If the QStyle has animations, animate
-    if (const int animationDuration = widget->style()->styleHint(QStyle::SH_Widget_Animation_Duration, 0, widget)) {
+    if (const int animationDuration = widget->style()->styleHint(QStyle::SH_Widget_Animation_Duration, nullptr, widget)) {
         AnimationMap::const_iterator it = m_animation_map.constFind(widget);
         if (it != m_animation_map.constEnd() && (*it)->endValue().toRect() == final_geometry)
             return;
diff --git a/src/widgets/widgets/qwidgetlinecontrol.cpp b/src/widgets/widgets/qwidgetlinecontrol.cpp
index 9cdae4f28f..a242947c11 100644
--- a/src/widgets/widgets/qwidgetlinecontrol.cpp
+++ b/src/widgets/widgets/qwidgetlinecontrol.cpp
@@ -964,7 +964,7 @@ void QWidgetLineControl::parseInputMask(const QString &maskFields)
     if (maskFields.isEmpty() || delimiter == 0) {
         if (m_maskData) {
             delete [] m_maskData;
-            m_maskData = 0;
+            m_maskData = nullptr;
             m_maxLength = 32767;
             internalSetText(QString(), -1, false);
         }
diff --git a/src/widgets/widgets/qwidgettextcontrol.cpp b/src/widgets/widgets/qwidgettextcontrol.cpp
index 1c169c3325..0b3c30312d 100644
--- a/src/widgets/widgets/qwidgettextcontrol.cpp
+++ b/src/widgets/widgets/qwidgettextcontrol.cpp
@@ -125,7 +125,7 @@ static QTextLine currentTextLine(const QTextCursor &cursor)
 }
 
 QWidgetTextControlPrivate::QWidgetTextControlPrivate()
-    : doc(0), cursorOn(false), cursorVisible(false), cursorIsFocusIndicator(false),
+    : doc(nullptr), cursorOn(false), cursorVisible(false), cursorIsFocusIndicator(false),
 #ifndef Q_OS_ANDROID
       interactionFlags(Qt::TextEditorInteraction),
 #else
@@ -683,7 +683,7 @@ void QWidgetTextControlPrivate::_q_contentsChanged(int from, int charsRemoved, i
         // always report the right number of removed chars, but in lack of the real string use spaces
         QString oldText = QString(charsRemoved, QLatin1Char(' '));
 
-        QAccessibleEvent *ev = 0;
+        QAccessibleEvent *ev = nullptr;
         if (charsRemoved == 0) {
             ev = new QAccessibleTextInsertEvent(q->parent(), from, newText);
         } else if (charsAdded == 0) {
@@ -906,12 +906,12 @@ void QWidgetTextControl::setDocument(QTextDocument *document)
 
     d->doc->disconnect(this);
     d->doc->documentLayout()->disconnect(this);
-    d->doc->documentLayout()->setPaintDevice(0);
+    d->doc->documentLayout()->setPaintDevice(nullptr);
 
     if (d->doc->parent() == this)
         delete d->doc;
 
-    d->doc = 0;
+    d->doc = nullptr;
     d->setContent(Qt::RichText, QString(), document);
 }
 
@@ -2302,7 +2302,7 @@ QMenu *QWidgetTextControl::createStandardContextMenu(const QPointF &pos, QWidget
         d->linkToCopy = anchorAt(pos);
 
     if (d->linkToCopy.isEmpty() && !showTextSelectionActions)
-        return 0;
+        return nullptr;
 
     QMenu *menu = new QMenu(parent);
     QAction *a;
@@ -2656,7 +2656,7 @@ void QWidgetTextControl::print(QPagedPaintDevice *printer) const
     Q_D(const QWidgetTextControl);
     if (!printer)
         return;
-    QTextDocument *tempDoc = 0;
+    QTextDocument *tempDoc = nullptr;
     const QTextDocument *doc = d->doc;
     if (QPagedPaintDevicePrivate::get(printer)->printSelectionOnly) {
         if (!d->cursor.hasSelection())