Merge remote-tracking branch 'qt/dev' into dev-highdpi

Conflicts:
	src/gui/kernel/qsimpledrag.cpp
	src/gui/kernel/qwindowsysteminterface.cpp
	src/gui/kernel/qwindowsysteminterface_p.h
	src/plugins/platforms/xcb/qxcbwindow.cpp

Change-Id: Icd887552ade61d6a2b2527383970f7145aa00faf

81 files changed, 1195 insertions, 372 deletions

diff --git a/src/widgets/accessible/itemviews.cpp b/src/widgets/accessible/itemviews.cpp
index 4f6cb56060..c7625c2827 100644
--- a/src/widgets/accessible/itemviews.cpp
+++ b/src/widgets/accessible/itemviews.cpp
@@ -1010,6 +1010,9 @@ QAccessible::Role QAccessibleTableCell::role() const
 QAccessible::State QAccessibleTableCell::state() const
 {
     QAccessible::State st;
+    if (!view)
+        return st;
+
     QRect globalRect = view->rect();
     globalRect.translate(view->mapToGlobal(QPoint(0,0)));
     if (!globalRect.intersects(rect()))
diff --git a/src/widgets/dialogs/qdialog.cpp b/src/widgets/dialogs/qdialog.cpp
index 65def6d4b8..6676a3ccba 100644
--- a/src/widgets/dialogs/qdialog.cpp
+++ b/src/widgets/dialogs/qdialog.cpp
@@ -534,7 +534,10 @@ int QDialog::exec()
 
     QPointer<QDialog> guard = this;
     if (d->nativeDialogInUse) {
-        d->platformHelper()->exec();
+        if (windowModality() == Qt::WindowModal)
+            d->platformHelper()->execModalForWindow(d->parentWindow());
+        else
+            d->platformHelper()->exec();
     } else {
         QEventLoop eventLoop;
         d->eventLoop = &eventLoop;
diff --git a/src/widgets/dialogs/qfiledialog.cpp b/src/widgets/dialogs/qfiledialog.cpp
index 1be2f93478..41522bfa19 100644
--- a/src/widgets/dialogs/qfiledialog.cpp
+++ b/src/widgets/dialogs/qfiledialog.cpp
@@ -893,6 +893,12 @@ void QFileDialogPrivate::_q_goToUrl(const QUrl &url)
 
 /*!
     Sets the file dialog's current \a directory.
+
+    \note On iOS, if you set \a directory to \l{QStandardPaths::standardLocations()}
+        {QStandardPaths::standardLocations(QStandardPaths::PicturesLocation).last()},
+        a native image picker dialog will be used for accessing the user's photo album.
+        The filename returned can be loaded using QFile and related APIs.
+        This feature was added in Qt 5.5.
 */
 void QFileDialog::setDirectory(const QString &directory)
 {
diff --git a/src/widgets/dialogs/qfileinfogatherer.cpp b/src/widgets/dialogs/qfileinfogatherer.cpp
index df07de7975..7329019a87 100644
--- a/src/widgets/dialogs/qfileinfogatherer.cpp
+++ b/src/widgets/dialogs/qfileinfogatherer.cpp
@@ -185,6 +185,8 @@ void QFileInfoGatherer::removePath(const QString &path)
 #ifndef QT_NO_FILESYSTEMWATCHER
     QMutexLocker locker(&mutex);
     watcher->removePath(path);
+#else
+    Q_UNUSED(path);
 #endif
 }
 
diff --git a/src/widgets/dialogs/qfilesystemmodel.cpp b/src/widgets/dialogs/qfilesystemmodel.cpp
index 04238f242a..4859231d95 100644
--- a/src/widgets/dialogs/qfilesystemmodel.cpp
+++ b/src/widgets/dialogs/qfilesystemmodel.cpp
@@ -544,7 +544,7 @@ QModelIndex QFileSystemModel::parent(const QModelIndex &index) const
 
     QFileSystemModelPrivate::QFileSystemNode *indexNode = d->node(index);
     Q_ASSERT(indexNode != 0);
-    QFileSystemModelPrivate::QFileSystemNode *parentNode = (indexNode ? indexNode->parent : 0);
+    QFileSystemModelPrivate::QFileSystemNode *parentNode = indexNode->parent;
     if (parentNode == 0 || parentNode == &d->root)
         return QModelIndex();
 
@@ -653,10 +653,12 @@ int QFileSystemModel::columnCount(const QModelIndex &parent) const
  */
 QVariant QFileSystemModel::myComputer(int role) const
 {
+#ifndef QT_NO_FILESYSTEMWATCHER
     Q_D(const QFileSystemModel);
+#endif
     switch (role) {
     case Qt::DisplayRole:
-        return d->myComputer();
+        return QFileSystemModelPrivate::myComputer();
 #ifndef QT_NO_FILESYSTEMWATCHER
     case Qt::DecorationRole:
         return d->fileInfoGatherer.iconProvider()->icon(QFileIconProvider::Computer);
diff --git a/src/widgets/dialogs/qwizard_win.cpp b/src/widgets/dialogs/qwizard_win.cpp
index 701fea1c03..a4b37f360b 100644
--- a/src/widgets/dialogs/qwizard_win.cpp
+++ b/src/widgets/dialogs/qwizard_win.cpp
@@ -361,6 +361,36 @@ bool QVistaHelper::setDWMTitleBar(TitleBarChangeType type)
 
 Q_GUI_EXPORT HICON qt_pixmapToWinHICON(const QPixmap &);
 
+static LOGFONT getCaptionLogFont(HANDLE hTheme)
+{
+    LOGFONT result = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, { 0 } };
+
+    if (!hTheme || FAILED(pGetThemeSysFont(hTheme, WIZ_TMT_CAPTIONFONT, &result))) {
+        NONCLIENTMETRICS ncm;
+        ncm.cbSize = sizeof(NONCLIENTMETRICS);
+        SystemParametersInfo(SPI_GETNONCLIENTMETRICS, sizeof(NONCLIENTMETRICS), &ncm, false);
+        result = ncm.lfMessageFont;
+    }
+    return result;
+}
+
+static bool getCaptionQFont(int dpi, QFont *result)
+{
+    if (!pOpenThemeData)
+        return false;
+    const HANDLE hTheme =
+        pOpenThemeData(QApplicationPrivate::getHWNDForWidget(QApplication::desktop()), L"WINDOW");
+    if (!hTheme)
+        return false;
+    // Call into QWindowsNativeInterface to convert the LOGFONT into a QFont.
+    const LOGFONT logFont = getCaptionLogFont(hTheme);
+    QPlatformNativeInterface *ni = QGuiApplication::platformNativeInterface();
+    return ni && QMetaObject::invokeMethod(ni, "logFontToQFont", Qt::DirectConnection,
+                                           Q_RETURN_ARG(QFont, *result),
+                                           Q_ARG(const void *, &logFont),
+                                           Q_ARG(int, dpi));
+}
+
 void QVistaHelper::drawTitleBar(QPainter *painter)
 {
     Q_ASSERT(backButton_);
@@ -378,7 +408,9 @@ void QVistaHelper::drawTitleBar(QPainter *painter)
     const int verticalCenter = (btnTop + btnHeight / 2) - 1;
 
     const QString text = wizard->window()->windowTitle();
-    const QFont font = QApplication::font("QMdiSubWindowTitleBar");
+    QFont font;
+    if (!isWindow || !getCaptionQFont(wizard->logicalDpiY() * wizard->devicePixelRatio(), &font))
+        font = QApplication::font("QMdiSubWindowTitleBar");
     const QFontMetrics fontMetrics(font);
     const QRect brect = fontMetrics.boundingRect(text);
     int textHeight = brect.height();
@@ -649,19 +681,6 @@ bool QVistaHelper::eventFilter(QObject *obj, QEvent *event)
      return false;
 }
 
-HFONT QVistaHelper::getCaptionFont(HANDLE hTheme)
-{
-    LOGFONT lf = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, { 0 } };
-
-    if (!hTheme || FAILED(pGetThemeSysFont(hTheme, WIZ_TMT_CAPTIONFONT, &lf))) {
-        NONCLIENTMETRICS ncm;
-        ncm.cbSize = sizeof(NONCLIENTMETRICS);
-        SystemParametersInfo(SPI_GETNONCLIENTMETRICS, sizeof(NONCLIENTMETRICS), &ncm, false);
-        lf = ncm.lfMessageFont;
-    }
-    return CreateFontIndirect(&lf);
-}
-
 // Return a HDC for the wizard along with the transformation if the
 // wizard is a child window.
 HDC QVistaHelper::backingStoreDC(const QWidget *wizard, QPoint *offset)
@@ -713,7 +732,8 @@ bool QVistaHelper::drawTitleText(QPainter *painter, const QString &text, const Q
         bmp = CreateDIBSection(hdc, &dib, DIB_RGB_COLORS, NULL, NULL, 0);
 
         // Set up the DC
-        HFONT hCaptionFont = getCaptionFont(hTheme);
+        const LOGFONT captionLogFont = getCaptionLogFont(hTheme);
+        const HFONT hCaptionFont = CreateFontIndirect(&captionLogFont);
         HBITMAP hOldBmp = (HBITMAP)SelectObject(dcMem, (HGDIOBJ) bmp);
         HFONT hOldFont = (HFONT)SelectObject(dcMem, (HGDIOBJ) hCaptionFont);
 
diff --git a/src/widgets/dialogs/qwizard_win_p.h b/src/widgets/dialogs/qwizard_win_p.h
index 8c36472bee..84b795d506 100644
--- a/src/widgets/dialogs/qwizard_win_p.h
+++ b/src/widgets/dialogs/qwizard_win_p.h
@@ -105,7 +105,6 @@ public:
     static HDC backingStoreDC(const QWidget *wizard, QPoint *offset);
 
 private:
-    static HFONT getCaptionFont(HANDLE hTheme);
     HWND wizardHWND() const;
     bool drawTitleText(QPainter *painter, const QString &text, const QRect &rect, HDC hdc);
     static bool drawBlackRect(const QRect &rect, HDC hdc);
diff --git a/src/widgets/doc/images/listview.png b/src/widgets/doc/images/listview.png
index fa49c52c62..fa49c52c62 100755..100644
--- a/src/widgets/doc/images/listview.png
+++ b/src/widgets/doc/images/listview.png
diff --git a/src/widgets/doc/images/modelview-combobox.png b/src/widgets/doc/images/modelview-combobox.png
index d172b413eb..d172b413eb 100755..100644
--- a/src/widgets/doc/images/modelview-combobox.png
+++ b/src/widgets/doc/images/modelview-combobox.png
diff --git a/src/widgets/doc/images/tableview.png b/src/widgets/doc/images/tableview.png
index 8be1b6ce62..8be1b6ce62 100755..100644
--- a/src/widgets/doc/images/tableview.png
+++ b/src/widgets/doc/images/tableview.png
diff --git a/src/widgets/doc/snippets/macmainwindow.mm b/src/widgets/doc/snippets/macmainwindow.mm
index e1df77089c..e1df77089c 100755..100644
--- a/src/widgets/doc/snippets/macmainwindow.mm
+++ b/src/widgets/doc/snippets/macmainwindow.mm
diff --git a/src/widgets/effects/qgraphicseffect.cpp b/src/widgets/effects/qgraphicseffect.cpp
index f53804e494..5a97be3d96 100644
--- a/src/widgets/effects/qgraphicseffect.cpp
+++ b/src/widgets/effects/qgraphicseffect.cpp
@@ -111,6 +111,10 @@
 #ifndef QT_NO_GRAPHICSEFFECT
 QT_BEGIN_NAMESPACE
 
+QGraphicsEffectPrivate::~QGraphicsEffectPrivate()
+{
+}
+
 /*!
     \internal
     \class QGraphicsEffectSource
diff --git a/src/widgets/effects/qgraphicseffect_p.h b/src/widgets/effects/qgraphicseffect_p.h
index 6e990cc52e..35264c0d30 100644
--- a/src/widgets/effects/qgraphicseffect_p.h
+++ b/src/widgets/effects/qgraphicseffect_p.h
@@ -142,6 +142,7 @@ class Q_WIDGETS_EXPORT QGraphicsEffectPrivate : public QObjectPrivate
     Q_DECLARE_PUBLIC(QGraphicsEffect)
 public:
     QGraphicsEffectPrivate() : source(0), isEnabled(1) {}
+    ~QGraphicsEffectPrivate();
 
     inline void setGraphicsEffectSource(QGraphicsEffectSource *newSource)
     {
diff --git a/src/widgets/graphicsview/qgraphicsitem.cpp b/src/widgets/graphicsview/qgraphicsitem.cpp
index cd30410097..1fdbe0fc18 100644
--- a/src/widgets/graphicsview/qgraphicsitem.cpp
+++ b/src/widgets/graphicsview/qgraphicsitem.cpp
@@ -10829,9 +10829,7 @@ void QGraphicsSimpleTextItem::paint(QPainter *painter, const QStyleOptionGraphic
         range.start = 0;
         range.length = layout.text().length();
         range.format.setTextOutline(d->pen);
-        QList<QTextLayout::FormatRange> formats;
-        formats.append(range);
-        layout.setAdditionalFormats(formats);
+        layout.setFormats(QVector<QTextLayout::FormatRange>(1, range));
     }
 
     setupTextLayout(&layout);
diff --git a/src/widgets/graphicsview/qgraphicsproxywidget.cpp b/src/widgets/graphicsview/qgraphicsproxywidget.cpp
index db4d18299b..08ea1ea0e3 100644
--- a/src/widgets/graphicsview/qgraphicsproxywidget.cpp
+++ b/src/widgets/graphicsview/qgraphicsproxywidget.cpp
@@ -269,8 +269,7 @@ void QGraphicsProxyWidgetPrivate::sendWidgetMouseEvent(QGraphicsSceneMouseEvent
     // Send mouse event.
     QMouseEvent mouseEvent(type, pos, receiver->mapTo(receiver->topLevelWidget(), pos.toPoint()),
                            receiver->mapToGlobal(pos.toPoint()),
-                           event->button(), event->buttons(), event->modifiers());
-    QGuiApplicationPrivate::setMouseEventSource(&mouseEvent, event->source());
+                           event->button(), event->buttons(), event->modifiers(), event->source());
 
     QWidget *embeddedMouseGrabberPtr = (QWidget *)embeddedMouseGrabber;
     QApplicationPrivate::sendMouseEvent(receiver, &mouseEvent, alienWidget, widget,
diff --git a/src/widgets/graphicsview/qgraphicsscene.h b/src/widgets/graphicsview/qgraphicsscene.h
index b025730bb1..68382bf498 100644
--- a/src/widgets/graphicsview/qgraphicsscene.h
+++ b/src/widgets/graphicsview/qgraphicsscene.h
@@ -282,6 +282,10 @@ protected:
                            QWidget *widget = 0);
 
 protected Q_SLOTS:
+    // ### Qt 6: make unconditional
+#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
+    virtual
+#endif
     bool focusNextPrevChild(bool next);
 
 Q_SIGNALS:
diff --git a/src/widgets/graphicsview/qgraphicstransform.cpp b/src/widgets/graphicsview/qgraphicstransform.cpp
index 67564b5a8b..fe963fbf3c 100644
--- a/src/widgets/graphicsview/qgraphicstransform.cpp
+++ b/src/widgets/graphicsview/qgraphicstransform.cpp
@@ -89,6 +89,11 @@
 
 #ifndef QT_NO_GRAPHICSVIEW
 QT_BEGIN_NAMESPACE
+
+QGraphicsTransformPrivate::~QGraphicsTransformPrivate()
+{
+}
+
 void QGraphicsTransformPrivate::setItem(QGraphicsItem *i)
 {
     if (item == i)
diff --git a/src/widgets/graphicsview/qgraphicstransform_p.h b/src/widgets/graphicsview/qgraphicstransform_p.h
index dde085935f..c81a95fd3d 100644
--- a/src/widgets/graphicsview/qgraphicstransform_p.h
+++ b/src/widgets/graphicsview/qgraphicstransform_p.h
@@ -51,12 +51,14 @@ QT_BEGIN_NAMESPACE
 
 class QGraphicsItem;
 
-class QGraphicsTransformPrivate : public QObjectPrivate {
+// ### Qt 6: unexport again, if QtQuick1's QDeclarativeTranslatePrivate is gone by then
+class Q_WIDGETS_EXPORT QGraphicsTransformPrivate : public QObjectPrivate {
 public:
     Q_DECLARE_PUBLIC(QGraphicsTransform)
 
     QGraphicsTransformPrivate()
         : QObjectPrivate(), item(0) {}
+    ~QGraphicsTransformPrivate();
 
     QGraphicsItem *item;
 
diff --git a/src/widgets/graphicsview/qgraphicsview.cpp b/src/widgets/graphicsview/qgraphicsview.cpp
index c270c4be88..decb455988 100644
--- a/src/widgets/graphicsview/qgraphicsview.cpp
+++ b/src/widgets/graphicsview/qgraphicsview.cpp
@@ -362,6 +362,10 @@ QGraphicsViewPrivate::QGraphicsViewPrivate()
     styleOptions.reserve(QGRAPHICSVIEW_PREALLOC_STYLE_OPTIONS);
 }
 
+QGraphicsViewPrivate::~QGraphicsViewPrivate()
+{
+}
+
 /*!
     \internal
 */
diff --git a/src/widgets/graphicsview/qgraphicsview_p.h b/src/widgets/graphicsview/qgraphicsview_p.h
index fec8336695..dcbffb1c39 100644
--- a/src/widgets/graphicsview/qgraphicsview_p.h
+++ b/src/widgets/graphicsview/qgraphicsview_p.h
@@ -63,6 +63,7 @@ class Q_WIDGETS_EXPORT QGraphicsViewPrivate : public QAbstractScrollAreaPrivate
     Q_DECLARE_PUBLIC(QGraphicsView)
 public:
     QGraphicsViewPrivate();
+    ~QGraphicsViewPrivate();
 
     void recalculateContentSize();
     void centerView(QGraphicsView::ViewportAnchor anchor);
diff --git a/src/widgets/graphicsview/qgraphicswidget_p.cpp b/src/widgets/graphicsview/qgraphicswidget_p.cpp
index 402d54d2d8..e9ab6dffec 100644
--- a/src/widgets/graphicsview/qgraphicswidget_p.cpp
+++ b/src/widgets/graphicsview/qgraphicswidget_p.cpp
@@ -64,9 +64,7 @@ void QGraphicsWidgetPrivate::init(QGraphicsItem *parentItem, Qt::WindowFlags wFl
     adjustWindowFlags(&wFlags);
     windowFlags = wFlags;
 
-    if (parentItem)
-        setParentItemHelper(parentItem, 0, 0);
-
+    q->setParentItem(parentItem);
     q->setSizePolicy(QSizePolicy(QSizePolicy::Preferred, QSizePolicy::Preferred, QSizePolicy::DefaultType));
     q->setGraphicsItem(q);
 
diff --git a/src/widgets/itemviews/qabstractitemview.cpp b/src/widgets/itemviews/qabstractitemview.cpp
index 2caf5d1eb3..5b955a6e14 100644
--- a/src/widgets/itemviews/qabstractitemview.cpp
+++ b/src/widgets/itemviews/qabstractitemview.cpp
@@ -1882,8 +1882,7 @@ void QAbstractItemView::mouseDoubleClickEvent(QMouseEvent *event)
         || (d->pressedIndex != index)) {
         QMouseEvent me(QEvent::MouseButtonPress,
                        event->localPos(), event->windowPos(), event->screenPos(),
-                       event->button(), event->buttons(), event->modifiers());
-        QGuiApplicationPrivate::setMouseEventSource(&me, event->source());
+                       event->button(), event->buttons(), event->modifiers(), event->source());
         mousePressEvent(&me);
         return;
     }
diff --git a/src/widgets/itemviews/qabstractitemview_p.h b/src/widgets/itemviews/qabstractitemview_p.h
index b792228312..016c50436b 100644
--- a/src/widgets/itemviews/qabstractitemview_p.h
+++ b/src/widgets/itemviews/qabstractitemview_p.h
@@ -168,8 +168,20 @@ public:
         QModelIndex index;
         int col = -1;
         int row = -1;
+        const QMimeData *mime = event->mimeData();
+
+        // Drag enter event shall always be accepted, if mime type and action match.
+        // Whether the data can actually be dropped will be checked in drag move.
+        if (event->type() == QEvent::DragEnter) {
+            const QStringList modelTypes = model->mimeTypes();
+            for (int i = 0; i < modelTypes.count(); ++i)
+                if (mime->hasFormat(modelTypes.at(i))
+                    && (event->dropAction() & model->supportedDropActions()))
+                    return true;
+        }
+
         if (dropOn(event, &row, &col, &index)) {
-            return model->canDropMimeData(event->mimeData(),
+            return model->canDropMimeData(mime,
                                           dragDropMode == QAbstractItemView::InternalMove ? Qt::MoveAction : event->dropAction(),
                                           row, col, index);
         }
diff --git a/src/widgets/itemviews/qcolumnview.cpp b/src/widgets/itemviews/qcolumnview.cpp
index 5c317bbb0c..0ee03035a4 100644
--- a/src/widgets/itemviews/qcolumnview.cpp
+++ b/src/widgets/itemviews/qcolumnview.cpp
@@ -878,7 +878,9 @@ QList<int> QColumnView::columnWidths() const
 {
     Q_D(const QColumnView);
     QList<int> list;
-    for (int i = 0; i < d->columns.count(); ++i)
+    const int columnCount = d->columns.count();
+    list.reserve(columnCount);
+    for (int i = 0; i < columnCount; ++i)
         list.append(d->columnSizes.at(i));
     return list;
 }
diff --git a/src/widgets/itemviews/qcolumnview_p.h b/src/widgets/itemviews/qcolumnview_p.h
index ed30b5f085..0c0bdb5d1f 100644
--- a/src/widgets/itemviews/qcolumnview_p.h
+++ b/src/widgets/itemviews/qcolumnview_p.h
@@ -89,6 +89,16 @@ public:
         QAbstractScrollArea::resizeEvent(event);
     }
 
+    void scrollContentsBy(int dx, int dy) Q_DECL_OVERRIDE
+    {
+        if (!previewWidget)
+            return;
+        scrollDirtyRegion(dx, dy);
+        viewport()->scroll(dx, dy);
+
+        QAbstractItemView::scrollContentsBy(dx, dy);
+    }
+
     QRect visualRect(const QModelIndex &) const Q_DECL_OVERRIDE
     {
         return QRect();
diff --git a/src/widgets/itemviews/qfileiconprovider.cpp b/src/widgets/itemviews/qfileiconprovider.cpp
index 1cc3a2a905..cab32619c5 100644
--- a/src/widgets/itemviews/qfileiconprovider.cpp
+++ b/src/widgets/itemviews/qfileiconprovider.cpp
@@ -117,6 +117,7 @@ public:
             if (themeSizes.isEmpty())
                 return sizes;
 
+            sizes.reserve(themeSizes.count());
             foreach (int size, themeSizes)
                 sizes << QSize(size, size);
         }
diff --git a/src/widgets/itemviews/qheaderview.cpp b/src/widgets/itemviews/qheaderview.cpp
index 66ff472724..bca315f80b 100644
--- a/src/widgets/itemviews/qheaderview.cpp
+++ b/src/widgets/itemviews/qheaderview.cpp
@@ -1879,13 +1879,13 @@ void QHeaderView::sectionsInserted(const QModelIndex &parent,
 
     // insert sections into hiddenSectionSize
     QHash<int, int> newHiddenSectionSize; // from logical index to section size
-    for (int i = 0; i < logicalFirst; ++i)
-        if (isSectionHidden(i))
-            newHiddenSectionSize[i] = d->hiddenSectionSize[i];
-    for (int j = logicalLast + 1; j < d->sectionCount(); ++j)
-        if (isSectionHidden(j))
-            newHiddenSectionSize[j] = d->hiddenSectionSize[j - insertCount];
-    d->hiddenSectionSize = newHiddenSectionSize;
+    for (QHash<int, int>::const_iterator it = d->hiddenSectionSize.cbegin(),
+         end = d->hiddenSectionSize.cend(); it != end; ++it) {
+        const int oldIndex = it.key();
+        const int newIndex = (oldIndex < logicalFirst) ? oldIndex : oldIndex + insertCount;
+        newHiddenSectionSize[newIndex] = it.value();
+    }
+    d->hiddenSectionSize.swap(newHiddenSectionSize);
 
     d->doDelayedResizeSections();
     emit sectionCountChanged(oldCount, count());
diff --git a/src/widgets/itemviews/qlistview.cpp b/src/widgets/itemviews/qlistview.cpp
index b7a4ec3925..9b07564db9 100644
--- a/src/widgets/itemviews/qlistview.cpp
+++ b/src/widgets/itemviews/qlistview.cpp
@@ -53,6 +53,8 @@
 
 QT_BEGIN_NAMESPACE
 
+extern bool qt_sendSpontaneousEvent(QObject *receiver, QEvent *event);
+
 /*!
     \class QListView
 
@@ -796,6 +798,35 @@ void QListView::mouseReleaseEvent(QMouseEvent *e)
     }
 }
 
+#ifndef QT_NO_WHEELEVENT
+/*!
+  \reimp
+*/
+void QListView::wheelEvent(QWheelEvent *e)
+{
+    Q_D(QListView);
+    if (e->orientation() == Qt::Vertical) {
+        if (e->angleDelta().x() == 0
+            && ((d->flow == TopToBottom && d->wrap) || (d->flow == LeftToRight && !d->wrap))
+            && d->vbar->minimum() == 0 && d->vbar->maximum() == 0) {
+            QPoint pixelDelta(e->pixelDelta().y(), e->pixelDelta().x());
+            QPoint angleDelta(e->angleDelta().y(), e->angleDelta().x());
+            QWheelEvent hwe(e->pos(), e->globalPos(), pixelDelta, angleDelta, e->delta(),
+                            Qt::Horizontal, e->buttons(), e->modifiers(), e->phase());
+            if (e->spontaneous())
+                qt_sendSpontaneousEvent(d->hbar, &hwe);
+            else
+                QApplication::sendEvent(d->hbar, &hwe);
+            e->setAccepted(hwe.isAccepted());
+        } else {
+            QApplication::sendEvent(d->vbar, e);
+        }
+    } else {
+        QApplication::sendEvent(d->hbar, e);
+    }
+}
+#endif // QT_NO_WHEELEVENT
+
 /*!
   \reimp
 */
@@ -1846,8 +1877,17 @@ void QCommonListViewBase::updateHorizontalScrollBar(const QSize &step)
     const bool bothScrollBarsAuto = qq->verticalScrollBarPolicy() == Qt::ScrollBarAsNeeded &&
                                     qq->horizontalScrollBarPolicy() == Qt::ScrollBarAsNeeded;
 
-    if (bothScrollBarsAuto && contentsSize.width() - qq->verticalScrollBar()->width() <= viewport()->width()
-                           && contentsSize.height() - qq->horizontalScrollBar()->height() <= viewport()->height()) {
+    const QSize viewportSize(viewport()->width() + (qq->verticalScrollBar()->maximum() > 0 ? qq->verticalScrollBar()->width() : 0),
+                             viewport()->height() + (qq->horizontalScrollBar()->maximum() > 0 ? qq->horizontalScrollBar()->height() : 0));
+
+    bool verticalWantsToShow = contentsSize.height() > viewportSize.height();
+    bool horizontalWantsToShow;
+    if (verticalWantsToShow)
+        horizontalWantsToShow = contentsSize.width() > viewportSize.width() - qq->verticalScrollBar()->width();
+    else
+        horizontalWantsToShow = contentsSize.width() > viewportSize.width();
+
+    if (bothScrollBarsAuto && !horizontalWantsToShow) {
         // break the infinite loop described above by setting the range to 0, 0.
         // QAbstractScrollArea will then hide the scroll bar for us
         horizontalScrollBar()->setRange(0, 0);
@@ -1868,8 +1908,17 @@ void QCommonListViewBase::updateVerticalScrollBar(const QSize &step)
     const bool bothScrollBarsAuto = qq->verticalScrollBarPolicy() == Qt::ScrollBarAsNeeded &&
                                     qq->horizontalScrollBarPolicy() == Qt::ScrollBarAsNeeded;
 
-    if (bothScrollBarsAuto && contentsSize.width() - qq->verticalScrollBar()->width() <= viewport()->width()
-                           && contentsSize.height() - qq->horizontalScrollBar()->height() <= viewport()->height()) {
+    const QSize viewportSize(viewport()->width() + (qq->verticalScrollBar()->maximum() > 0 ? qq->verticalScrollBar()->width() : 0),
+                             viewport()->height() + (qq->horizontalScrollBar()->maximum() > 0 ? qq->horizontalScrollBar()->height() : 0));
+
+    bool horizontalWantsToShow = contentsSize.width() > viewportSize.width();
+    bool verticalWantsToShow;
+    if (horizontalWantsToShow)
+        verticalWantsToShow = contentsSize.height() > viewportSize.height() - qq->horizontalScrollBar()->height();
+    else
+        verticalWantsToShow = contentsSize.height() > viewportSize.height();
+
+    if (bothScrollBarsAuto && !verticalWantsToShow) {
         // break the infinite loop described above by setting the range to 0, 0.
         // QAbstractScrollArea will then hide the scroll bar for us
         verticalScrollBar()->setRange(0, 0);
diff --git a/src/widgets/itemviews/qlistview.h b/src/widgets/itemviews/qlistview.h
index f62c96067f..ac65a47d9f 100644
--- a/src/widgets/itemviews/qlistview.h
+++ b/src/widgets/itemviews/qlistview.h
@@ -146,6 +146,9 @@ protected:
 
     void mouseMoveEvent(QMouseEvent *e) Q_DECL_OVERRIDE;
     void mouseReleaseEvent(QMouseEvent *e) Q_DECL_OVERRIDE;
+#ifndef QT_NO_WHEELEVENT
+    void wheelEvent(QWheelEvent *e) Q_DECL_OVERRIDE;
+#endif
 
     void timerEvent(QTimerEvent *e) Q_DECL_OVERRIDE;
     void resizeEvent(QResizeEvent *e) Q_DECL_OVERRIDE;
diff --git a/src/widgets/itemviews/qlistwidget.cpp b/src/widgets/itemviews/qlistwidget.cpp
index 66f965aa54..668bfda59d 100644
--- a/src/widgets/itemviews/qlistwidget.cpp
+++ b/src/widgets/itemviews/qlistwidget.cpp
@@ -299,7 +299,10 @@ void QListModel::sort(int column, Qt::SortOrder order)
     std::sort(sorting.begin(), sorting.end(), compare);
     QModelIndexList fromIndexes;
     QModelIndexList toIndexes;
-    for (int r = 0; r < sorting.count(); ++r) {
+    const int sortingCount = sorting.count();
+    fromIndexes.reserve(sortingCount);
+    toIndexes.reserve(sortingCount);
+    for (int r = 0; r < sortingCount; ++r) {
         QListWidgetItem *item = sorting.at(r).first;
         toIndexes.append(createIndex(r, 0, item));
         fromIndexes.append(createIndex(sorting.at(r).second, 0, sorting.at(r).first));
@@ -423,7 +426,9 @@ QMimeData *QListModel::internalMimeData()  const
 QMimeData *QListModel::mimeData(const QModelIndexList &indexes) const
 {
     QList<QListWidgetItem*> itemlist;
-    for (int i = 0; i < indexes.count(); ++i)
+    const int indexesCount = indexes.count();
+    itemlist.reserve(indexesCount);
+    for (int i = 0; i < indexesCount; ++i)
         itemlist << at(indexes.at(i).row());
     const QListWidget *view = qobject_cast<const QListWidget*>(QObject::parent());
 
@@ -1710,7 +1715,9 @@ QList<QListWidgetItem*> QListWidget::findItems(const QString &text, Qt::MatchFla
     QModelIndexList indexes = d->listModel()->match(model()->index(0, 0, QModelIndex()),
                                                 Qt::DisplayRole, text, -1, flags);
     QList<QListWidgetItem*> items;
-    for (int i = 0; i < indexes.size(); ++i)
+    const int indexesSize = indexes.size();
+    items.reserve(indexesSize);
+    for (int i = 0; i < indexesSize; ++i)
         items.append(d->listModel()->at(indexes.at(i).row()));
     return items;
 }
@@ -1795,6 +1802,7 @@ QMimeData *QListWidget::mimeData(const QList<QListWidgetItem*> items) const
 
     // if non empty, it's called from the model's own mimeData
     if (cachedIndexes.isEmpty()) {
+        cachedIndexes.reserve(items.count());
         foreach (QListWidgetItem *item, items)
             cachedIndexes << indexFromItem(item);
 
@@ -1845,7 +1853,9 @@ void QListWidget::dropEvent(QDropEvent *event) {
         if (d->dropOn(event, &row, &col, &topIndex)) {
             QList<QModelIndex> selIndexes = selectedIndexes();
             QList<QPersistentModelIndex> persIndexes;
-            for (int i = 0; i < selIndexes.count(); i++)
+            const int selIndexesCount = selIndexes.count();
+            persIndexes.reserve(selIndexesCount);
+            for (int i = 0; i < selIndexesCount; i++)
                 persIndexes.append(selIndexes.at(i));
 
             if (persIndexes.contains(topIndex))
diff --git a/src/widgets/itemviews/qtablewidget.cpp b/src/widgets/itemviews/qtablewidget.cpp
index 9ebcbc35a7..b2d4abe5ac 100644
--- a/src/widgets/itemviews/qtablewidget.cpp
+++ b/src/widgets/itemviews/qtablewidget.cpp
@@ -812,7 +812,9 @@ QMimeData *QTableModel::internalMimeData()  const
 QMimeData *QTableModel::mimeData(const QModelIndexList &indexes) const
 {
     QList<QTableWidgetItem*> items;
-    for (int i = 0; i < indexes.count(); ++i)
+    const int indexesCount = indexes.count();
+    items.reserve(indexesCount);
+    for (int i = 0; i < indexesCount; ++i)
         items << item(indexes.at(i));
     const QTableWidget *view = qobject_cast<const QTableWidget*>(QObject::parent());
 
@@ -2326,7 +2328,9 @@ QList<QTableWidgetSelectionRange> QTableWidget::selectedRanges() const
 {
     const QList<QItemSelectionRange> ranges = selectionModel()->selection();
     QList<QTableWidgetSelectionRange> result;
-    for (int i = 0; i < ranges.count(); ++i)
+    const int rangesCount = ranges.count();
+    result.reserve(rangesCount);
+    for (int i = 0; i < rangesCount; ++i)
         result.append(QTableWidgetSelectionRange(ranges.at(i).top(),
                                                  ranges.at(i).left(),
                                                  ranges.at(i).bottom(),
@@ -2372,7 +2376,9 @@ QList<QTableWidgetItem*> QTableWidget::findItems(const QString &text, Qt::MatchF
         indexes += d->model->match(model()->index(0, column, QModelIndex()),
                                      Qt::DisplayRole, text, -1, flags);
     QList<QTableWidgetItem*> items;
-    for (int i = 0; i < indexes.size(); ++i)
+    const int indexCount = indexes.size();
+    items.reserve(indexCount);
+    for (int i = 0; i < indexCount; ++i)
         items.append(d->tableModel()->item(indexes.at(i)));
     return items;
 }
@@ -2565,6 +2571,7 @@ QMimeData *QTableWidget::mimeData(const QList<QTableWidgetItem*> items) const
 
     // if non empty, it's called from the model's own mimeData
     if (cachedIndexes.isEmpty()) {
+        cachedIndexes.reserve(items.count());
         foreach (QTableWidgetItem *item, items)
             cachedIndexes << indexFromItem(item);
 
@@ -2676,7 +2683,9 @@ void QTableWidget::dropEvent(QDropEvent *event) {
             }
 
             QList<QTableWidgetItem *> taken;
-            for (int i = 0; i < indexes.count(); ++i)
+            const int indexesCount = indexes.count();
+            taken.reserve(indexesCount);
+            for (int i = 0; i < indexesCount; ++i)
                 taken.append(takeItem(indexes.at(i).row(), indexes.at(i).column()));
 
             for (int i = 0; i < indexes.count(); ++i) {
diff --git a/src/widgets/itemviews/qtreeview.cpp b/src/widgets/itemviews/qtreeview.cpp
index 43db43fcd4..9b3e270fdd 100644
--- a/src/widgets/itemviews/qtreeview.cpp
+++ b/src/widgets/itemviews/qtreeview.cpp
@@ -3658,6 +3658,7 @@ void QTreeViewPrivate::updateScrollBars()
     if (!viewportSize.isValid())
         viewportSize = QSize(0, 0);
 
+    executePostedLayout();
     if (viewItems.isEmpty()) {
         q->doItemsLayout();
     }
diff --git a/src/widgets/itemviews/qtreewidget.cpp b/src/widgets/itemviews/qtreewidget.cpp
index 1366a00318..5970e94292 100644
--- a/src/widgets/itemviews/qtreewidget.cpp
+++ b/src/widgets/itemviews/qtreewidget.cpp
@@ -3042,7 +3042,9 @@ QList<QTreeWidgetItem*> QTreeWidget::findItems(const QString &text, Qt::MatchFla
     QModelIndexList indexes = d->model->match(model()->index(0, column, QModelIndex()),
                                                 Qt::DisplayRole, text, -1, flags);
     QList<QTreeWidgetItem*> items;
-    for (int i = 0; i < indexes.size(); ++i)
+    const int indexesSize = indexes.size();
+    items.reserve(indexesSize);
+    for (int i = 0; i < indexesSize; ++i)
         items.append(d->item(indexes.at(i)));
     return items;
 }
@@ -3371,7 +3373,9 @@ void QTreeWidget::dropEvent(QDropEvent *event) {
         if (d->dropOn(event, &row, &col, &topIndex)) {
             QList<QModelIndex> idxs = selectedIndexes();
             QList<QPersistentModelIndex> indexes;
-            for (int i = 0; i < idxs.count(); i++)
+            const int indexesCount = idxs.count();
+            indexes.reserve(indexesCount);
+            for (int i = 0; i < indexesCount; i++)
                 indexes.append(idxs.at(i));
 
             if (indexes.contains(topIndex))
diff --git a/src/widgets/kernel/kernel.pri b/src/widgets/kernel/kernel.pri
index 88c1e2595b..21a982f349 100644
--- a/src/widgets/kernel/kernel.pri
+++ b/src/widgets/kernel/kernel.pri
@@ -49,6 +49,7 @@ SOURCES += \
 	kernel/qlayoutengine.cpp \
 	kernel/qlayoutitem.cpp \
         kernel/qshortcut.cpp \
+        kernel/qsizepolicy.cpp \
         kernel/qstackedlayout.cpp \
 	kernel/qtooltip.cpp \
 	kernel/qwhatsthis.cpp \
diff --git a/src/widgets/kernel/qapplication.cpp b/src/widgets/kernel/qapplication.cpp
index dd7474b930..f457993168 100644
--- a/src/widgets/kernel/qapplication.cpp
+++ b/src/widgets/kernel/qapplication.cpp
@@ -3250,12 +3250,11 @@ bool QApplication::notify(QObject *receiver, QEvent *e)
 
             QPointer<QWidget> pw = w;
             while (w) {
-                QMouseEvent me(mouse->type(), relpos, mouse->windowPos(), mouse->globalPos(), mouse->button(), mouse->buttons(),
-                               mouse->modifiers());
+                QMouseEvent me(mouse->type(), relpos, mouse->windowPos(), mouse->globalPos(),
+                               mouse->button(), mouse->buttons(), mouse->modifiers(), mouse->source());
                 me.spont = mouse->spontaneous();
                 me.setTimestamp(mouse->timestamp());
                 QGuiApplicationPrivate::setMouseEventFlags(&me, mouse->flags());
-                QGuiApplicationPrivate::setMouseEventSource(&me, mouse->source());
                 // throw away any mouse-tracking-only mouse events
                 if (!w->hasMouseTracking()
                     && mouse->type() == QEvent::MouseMove && mouse->buttons() == 0) {
@@ -4273,15 +4272,16 @@ void QApplicationPrivate::cleanupMultitouch_sys()
 {
 }
 
-QWidget *QApplicationPrivate::findClosestTouchPointTarget(QTouchDevice *device, const QPointF &screenPos)
+QWidget *QApplicationPrivate::findClosestTouchPointTarget(QTouchDevice *device, const QTouchEvent::TouchPoint &touchPoint)
 {
+    const QPointF screenPos = touchPoint.screenPos();
     int closestTouchPointId = -1;
     QObject *closestTarget = 0;
     qreal closestDistance = qreal(0.);
     QHash<ActiveTouchPointsKey, ActiveTouchPointsValue>::const_iterator it = activeTouchPoints.constBegin(),
             ite = activeTouchPoints.constEnd();
     while (it != ite) {
-        if (it.key().device == device) {
+        if (it.key().device == device && it.key().touchPointId != touchPoint.id()) {
             const QTouchEvent::TouchPoint &touchPoint = it->touchPoint;
             qreal dx = screenPos.x() - touchPoint.screenPos().x();
             qreal dy = screenPos.y() - touchPoint.screenPos().y();
@@ -4337,7 +4337,7 @@ bool QApplicationPrivate::translateRawTouchEvent(QWidget *window,
             }
 
             if (device->type() == QTouchDevice::TouchScreen) {
-                QWidget *closestWidget = d->findClosestTouchPointTarget(device, touchPoint.screenPos());
+                QWidget *closestWidget = d->findClosestTouchPointTarget(device, touchPoint);
                 QWidget *widget = static_cast<QWidget *>(target.data());
                 if (closestWidget
                         && (widget->isAncestorOf(closestWidget) || closestWidget->isAncestorOf(widget))) {
@@ -4357,8 +4357,10 @@ bool QApplicationPrivate::translateRawTouchEvent(QWidget *window,
 
 #ifdef Q_OS_OSX
         // Single-touch events are normally not sent unless WA_TouchPadAcceptSingleTouchEvents is set.
-        // In Qt 4 this check was in OS X-only coode. That behavior is preserved here by the #ifdef.
-        if (touchPoints.count() == 1 && !targetWidget->testAttribute(Qt::WA_TouchPadAcceptSingleTouchEvents))
+        // In Qt 4 this check was in OS X-only code. That behavior is preserved here by the #ifdef.
+        if (touchPoints.count() == 1
+            && device->type() == QTouchDevice::TouchPad
+            && !targetWidget->testAttribute(Qt::WA_TouchPadAcceptSingleTouchEvents))
             continue;
 #endif
 
@@ -4374,7 +4376,7 @@ bool QApplicationPrivate::translateRawTouchEvent(QWidget *window,
     QHash<QWidget *, StatesAndTouchPoints>::ConstIterator it = widgetsNeedingEvents.constBegin();
     const QHash<QWidget *, StatesAndTouchPoints>::ConstIterator end = widgetsNeedingEvents.constEnd();
     for (; it != end; ++it) {
-        QWidget *widget = it.key();
+        const QPointer<QWidget> widget = it.key();
         if (!QApplicationPrivate::tryModalHelper(widget, 0))
             continue;
 
@@ -4414,7 +4416,8 @@ bool QApplicationPrivate::translateRawTouchEvent(QWidget *window,
             // has been implicitly accepted and continue to send touch events
             if (QApplication::sendSpontaneousEvent(widget, &touchEvent) && touchEvent.isAccepted()) {
                 accepted = true;
-                widget->setAttribute(Qt::WA_WState_AcceptedTouchBeginEvent);
+                if (!widget.isNull())
+                    widget->setAttribute(Qt::WA_WState_AcceptedTouchBeginEvent);
             }
             break;
         }
diff --git a/src/widgets/kernel/qapplication_p.h b/src/widgets/kernel/qapplication_p.h
index 46359d7940..ba8d7ff63c 100644
--- a/src/widgets/kernel/qapplication_p.h
+++ b/src/widgets/kernel/qapplication_p.h
@@ -280,7 +280,7 @@ public:
     void initializeMultitouch_sys();
     void cleanupMultitouch();
     void cleanupMultitouch_sys();
-    QWidget *findClosestTouchPointTarget(QTouchDevice *device, const QPointF &screenPos);
+    QWidget *findClosestTouchPointTarget(QTouchDevice *device, const QTouchEvent::TouchPoint &touchPoint);
     void appendTouchPoint(const QTouchEvent::TouchPoint &touchPoint);
     void removeTouchPoint(int touchPointId);
     static bool translateRawTouchEvent(QWidget *widget,
diff --git a/src/widgets/kernel/qgesture.cpp b/src/widgets/kernel/qgesture.cpp
index 713a019cc3..7b7d465070 100644
--- a/src/widgets/kernel/qgesture.cpp
+++ b/src/widgets/kernel/qgesture.cpp
@@ -36,7 +36,7 @@
 #include "private/qstandardgestures_p.h"
 #include "qgraphicsview.h"
 
-#include <QtCore/QDebug>
+#include <private/qdebug_p.h>
 #ifndef QT_NO_GESTURES
 
 QT_BEGIN_NAMESPACE
@@ -1091,9 +1091,12 @@ QPointF QGestureEvent::mapToGraphicsScene(const QPointF &gesturePoint) const
 
 static void formatGestureHeader(QDebug d, const char *className, const QGesture *gesture)
 {
-     d << className << "(state=" << gesture->state();
-     if (gesture->hasHotSpot())
-         d << ",hotSpot=" << gesture->hotSpot();
+     d << className << "(state=";
+     QtDebugUtils::formatQEnum(d, gesture->state());
+     if (gesture->hasHotSpot()) {
+         d << ",hotSpot=";
+         QtDebugUtils::formatQPoint(d, gesture->hotSpot());
+     }
 }
 
 Q_WIDGETS_EXPORT QDebug operator<<(QDebug d, const QGesture *gesture)
@@ -1103,31 +1106,42 @@ Q_WIDGETS_EXPORT QDebug operator<<(QDebug d, const QGesture *gesture)
     switch (gesture->gestureType()) {
     case Qt::TapGesture:
         formatGestureHeader(d, "QTapGesture", gesture);
-        d << ",position=" << static_cast<const QTapGesture*>(gesture)->position() << ')';
+        d << ",position=";
+        QtDebugUtils::formatQPoint(d, static_cast<const QTapGesture*>(gesture)->position());
+        d << ')';
         break;
     case Qt::TapAndHoldGesture: {
         const QTapAndHoldGesture *tap = static_cast<const QTapAndHoldGesture*>(gesture);
         formatGestureHeader(d, "QTapAndHoldGesture", tap);
-        d << ",position=" << tap->position() << ",timeout=" << tap->timeout() << ')';
+        d << ",position=";
+        QtDebugUtils::formatQPoint(d, tap->position());
+        d << ",timeout=" << tap->timeout() << ')';
     }
         break;
     case Qt::PanGesture: {
         const QPanGesture *pan = static_cast<const QPanGesture*>(gesture);
         formatGestureHeader(d, "QPanGesture", pan);
-        d << ",lastOffset=" << pan->lastOffset() << ",offset=" << pan->offset()
-            << ",acceleration=" << pan->acceleration()
-            << ",delta=" << pan->delta() << ')';
+        d << ",lastOffset=";
+        QtDebugUtils::formatQPoint(d, pan->lastOffset());
+        d << pan->lastOffset();
+        d << ",offset=";
+        QtDebugUtils::formatQPoint(d, pan->offset());
+        d  << ",acceleration=" << pan->acceleration() << ",delta=";
+        QtDebugUtils::formatQPoint(d, pan->delta());
+        d << ')';
     }
         break;
     case Qt::PinchGesture: {
         const QPinchGesture *pinch = static_cast<const QPinchGesture*>(gesture);
         formatGestureHeader(d, "QPinchGesture", pinch);
         d << ",totalChangeFlags=" << pinch->totalChangeFlags()
-            << ",changeFlags=" << pinch->changeFlags()
-            << ",startCenterPoint=" << pinch->startCenterPoint()
-            << ",lastCenterPoint=" << pinch->lastCenterPoint()
-            << ",centerPoint=" << pinch->centerPoint()
-            << ",totalScaleFactor=" << pinch->totalScaleFactor()
+          << ",changeFlags=" << pinch->changeFlags() << ",startCenterPoint=";
+        QtDebugUtils::formatQPoint(d, pinch->startCenterPoint());
+        d << ",lastCenterPoint=";
+        QtDebugUtils::formatQPoint(d, pinch->lastCenterPoint());
+        d << ",centerPoint=";
+        QtDebugUtils::formatQPoint(d, pinch->centerPoint());
+        d << ",totalScaleFactor=" << pinch->totalScaleFactor()
             << ",lastScaleFactor=" << pinch->lastScaleFactor()
             << ",scaleFactor=" << pinch->scaleFactor()
             << ",totalRotationAngle=" << pinch->totalRotationAngle()
@@ -1138,9 +1152,11 @@ Q_WIDGETS_EXPORT QDebug operator<<(QDebug d, const QGesture *gesture)
     case Qt::SwipeGesture: {
         const QSwipeGesture *swipe = static_cast<const QSwipeGesture*>(gesture);
         formatGestureHeader(d, "QSwipeGesture", swipe);
-        d << ",horizontalDirection=" << swipe->horizontalDirection()
-            << ",verticalDirection=" << swipe->verticalDirection()
-            << ",swipeAngle=" << swipe->swipeAngle() << ')';
+        d << ",horizontalDirection=";
+        QtDebugUtils::formatQEnum(d, swipe->horizontalDirection());
+        d << ",verticalDirection=";
+        QtDebugUtils::formatQEnum(d, swipe->verticalDirection());
+        d << ",swipeAngle=" << swipe->swipeAngle() << ')';
     }
         break;
     default:
diff --git a/src/widgets/kernel/qlayout.cpp b/src/widgets/kernel/qlayout.cpp
index dcacea4777..e74f17b6f7 100644
--- a/src/widgets/kernel/qlayout.cpp
+++ b/src/widgets/kernel/qlayout.cpp
@@ -1470,85 +1470,4 @@ QSize QLayout::closestAcceptableSize(const QWidget *widget, const QSize &size)
     return result;
 }
 
-void QSizePolicy::setControlType(ControlType type)
-{
-    /*
-        The control type is a flag type, with values 0x1, 0x2, 0x4, 0x8, 0x10,
-        etc. In memory, we pack it onto the available bits (CTSize) in
-        setControlType(), and unpack it here.
-
-        Example:
-
-            0x00000001 maps to 0
-            0x00000002 maps to 1
-            0x00000004 maps to 2
-            0x00000008 maps to 3
-            etc.
-    */
-
-    int i = 0;
-    while (true) {
-        if (type & (0x1 << i)) {
-            bits.ctype = i;
-            return;
-        }
-        ++i;
-    }
-}
-
-QSizePolicy::ControlType QSizePolicy::controlType() const
-{
-    return QSizePolicy::ControlType(1 << bits.ctype);
-}
-
-#ifndef QT_NO_DATASTREAM
-
-/*!
-    \relates QSizePolicy
-    \since 4.2
-
-    Writes the size \a policy to the data stream \a stream.
-
-    \sa{Serializing Qt Data Types}{Format of the QDataStream operators}
-*/
-QDataStream &operator<<(QDataStream &stream, const QSizePolicy &policy)
-{
-    // The order here is for historical reasons. (compatibility with Qt4)
-    quint32 data = (policy.bits.horPolicy |         // [0, 3]
-                    policy.bits.verPolicy << 4 |    // [4, 7]
-                    policy.bits.hfw << 8 |          // [8]
-                    policy.bits.ctype << 9 |        // [9, 13]
-                    policy.bits.wfh << 14 |         // [14]
-                    policy.bits.retainSizeWhenHidden << 15 |     // [15]
-                    policy.bits.verStretch << 16 |  // [16, 23]
-                    policy.bits.horStretch << 24);  // [24, 31]
-    return stream << data;
-}
-
-#define VALUE_OF_BITS(data, bitstart, bitcount) ((data >> bitstart) & ((1 << bitcount) -1))
-
-/*!
-    \relates QSizePolicy
-    \since 4.2
-
-    Reads the size \a policy from the data stream \a stream.
-
-    \sa{Serializing Qt Data Types}{Format of the QDataStream operators}
-*/
-QDataStream &operator>>(QDataStream &stream, QSizePolicy &policy)
-{
-    quint32 data;
-    stream >> data;
-    policy.bits.horPolicy =  VALUE_OF_BITS(data, 0, 4);
-    policy.bits.verPolicy =  VALUE_OF_BITS(data, 4, 4);
-    policy.bits.hfw =        VALUE_OF_BITS(data, 8, 1);
-    policy.bits.ctype =      VALUE_OF_BITS(data, 9, 5);
-    policy.bits.wfh =        VALUE_OF_BITS(data, 14, 1);
-    policy.bits.retainSizeWhenHidden =    VALUE_OF_BITS(data, 15, 1);
-    policy.bits.verStretch = VALUE_OF_BITS(data, 16, 8);
-    policy.bits.horStretch = VALUE_OF_BITS(data, 24, 8);
-    return stream;
-}
-#endif // QT_NO_DATASTREAM
-
 QT_END_NAMESPACE
diff --git a/src/widgets/kernel/qlayoutitem.cpp b/src/widgets/kernel/qlayoutitem.cpp
index b21925e1d4..21f4c9a221 100644
--- a/src/widgets/kernel/qlayoutitem.cpp
+++ b/src/widgets/kernel/qlayoutitem.cpp
@@ -34,7 +34,6 @@
 #include "qlayout.h"
 
 #include "qapplication.h"
-#include "qdebug.h"
 #include "qlayoutengine_p.h"
 #include "qmenubar.h"
 #include "qtoolbar.h"
@@ -68,14 +67,6 @@ inline static QSize toLayoutItemSize(QWidgetPrivate *priv, const QSize &size)
 }
 
 /*!
-   Returns a QVariant storing this QSizePolicy.
-*/
-QSizePolicy::operator QVariant() const
-{
-    return QVariant(QVariant::SizePolicy, this);
-}
-
-/*!
     \class QLayoutItem
     \brief The QLayoutItem class provides an abstract item that a
     QLayout manipulates.
@@ -847,14 +838,4 @@ int QWidgetItemV2::heightForWidth(int width) const
     return height;
 }
 
-#ifndef QT_NO_DEBUG_STREAM
-QDebug operator<<(QDebug dbg, const QSizePolicy &p)
-{
-    QDebugStateSaver saver(dbg);
-    dbg.nospace() << "QSizePolicy(horizontalPolicy = " << p.horizontalPolicy()
-                  << ", verticalPolicy = " << p.verticalPolicy() << ')';
-    return dbg;
-}
-#endif
-
 QT_END_NAMESPACE
diff --git a/src/widgets/kernel/qopenglwidget.cpp b/src/widgets/kernel/qopenglwidget.cpp
index 7e4efc0e77..14e0abf7c7 100644
--- a/src/widgets/kernel/qopenglwidget.cpp
+++ b/src/widgets/kernel/qopenglwidget.cpp
@@ -104,6 +104,12 @@ QT_BEGIN_NAMESPACE
   non-sharable. To overcome this issue, prefer using
   QSurfaceFormat::setDefaultFormat() instead of setFormat().
 
+  \note Calling QSurfaceFormat::setDefaultFormat() before constructing
+  the QApplication instance is mandatory on some platforms (for example,
+  OS X) when an OpenGL core profile context is requested. This is to
+  ensure that resource sharing between contexts stays functional as all
+  internal contexts are created using the correct version and profile.
+
   \section1 Painting Techniques
 
   As described above, subclass QOpenGLWidget to render pure 3D content in the
@@ -739,6 +745,7 @@ void QOpenGLWidgetPrivate::initialize()
     QScopedPointer<QOpenGLContext> ctx(new QOpenGLContext);
     ctx->setShareContext(shareContext);
     ctx->setFormat(requestedFormat);
+    ctx->setScreen(shareContext->screen());
     if (!ctx->create()) {
         qWarning("QOpenGLWidget: Failed to create context");
         return;
@@ -762,6 +769,7 @@ void QOpenGLWidgetPrivate::initialize()
     // in QQuickWidget, use a dedicated QOffscreenSurface.
     surface = new QOffscreenSurface;
     surface->setFormat(ctx->format());
+    surface->setScreen(ctx->screen());
     surface->create();
 
     if (!ctx->makeCurrent(surface)) {
diff --git a/src/widgets/kernel/qsizepolicy.qdoc b/src/widgets/kernel/qsizepolicy.cpp
index e84412bc46..1476b4c5d7 100644
--- a/src/widgets/kernel/qsizepolicy.qdoc
+++ b/src/widgets/kernel/qsizepolicy.cpp
@@ -3,9 +3,9 @@
 ** Copyright (C) 2015 The Qt Company Ltd.
 ** Contact: http://www.qt.io/licensing/
 **
-** This file is part of the documentation of the Qt Toolkit.
+** This file is part of the QtWidgets module of the Qt Toolkit.
 **
-** $QT_BEGIN_LICENSE:FDL$
+** $QT_BEGIN_LICENSE:LGPL21$
 ** Commercial License Usage
 ** Licensees holding valid commercial Qt licenses may use this file in
 ** accordance with the commercial license agreement provided with the
@@ -14,17 +14,31 @@
 ** and conditions see http://www.qt.io/terms-conditions. For further
 ** information use the contact form at http://www.qt.io/contact-us.
 **
-** GNU Free Documentation License Usage
-** Alternatively, this file may be used under the terms of the GNU Free
-** Documentation License version 1.3 as published by the Free Software
-** Foundation and appearing in the file included in the packaging of
-** this file. Please review the following information to ensure
-** the GNU Free Documentation License version 1.3 requirements
-** will be met: http://www.gnu.org/copyleft/fdl.html.
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
 ** $QT_END_LICENSE$
 **
 ****************************************************************************/
 
+#include "qsizepolicy.h"
+
+#include <qdatastream.h>
+#include <qdebug.h>
+#include <qvariant.h>
+
+QT_BEGIN_NAMESPACE
+
 /*!
     \class QSizePolicy
     \brief The QSizePolicy class is a layout attribute describing horizontal
@@ -207,15 +221,18 @@
 */
 
 /*!
-    \fn ControlType QSizePolicy::controlType() const
     \since 4.3
 
     Returns the control type associated with the widget for which
     this size policy applies.
 */
+QSizePolicy::ControlType QSizePolicy::controlType() const
+{
+    return QSizePolicy::ControlType(1 << bits.ctype);
+}
+
 
 /*!
-    \fn void QSizePolicy::setControlType(ControlType type)
     \since 4.3
 
     Sets the control type associated with the widget for which this
@@ -230,6 +247,31 @@
 
     \sa QStyle::layoutSpacing()
 */
+void QSizePolicy::setControlType(ControlType type)
+{
+    /*
+        The control type is a flag type, with values 0x1, 0x2, 0x4, 0x8, 0x10,
+        etc. In memory, we pack it onto the available bits (CTSize) in
+        setControlType(), and unpack it here.
+
+        Example:
+
+            0x00000001 maps to 0
+            0x00000002 maps to 1
+            0x00000004 maps to 2
+            0x00000008 maps to 3
+            etc.
+    */
+
+    int i = 0;
+    while (true) {
+        if (type & (0x1 << i)) {
+            bits.ctype = i;
+            return;
+        }
+        ++i;
+    }
+}
 
 /*!
     \fn void QSizePolicy::setHeightForWidth(bool dependent)
@@ -344,7 +386,8 @@
     \fn void QSizePolicy::retainSizeWhenHidden() const
     \since 5.2
 
-    Returns if the layout should retain the widgets size when it is hidden. This is by default false.
+    Returns whether the layout should retain the widget's size when it is hidden.
+    This is \c false by default.
 
     \sa setRetainSizeWhenHidden()
 */
@@ -353,8 +396,8 @@
    \fn void QSizePolicy::setRetainSizeWhenHidden(bool retainSize)
    \since 5.2
 
-    Set if a layout should retain the widgets size when it is hidden.
-    If \a retainSize is true the layout will not be changed by hiding the widget.
+    Sets whether a layout should retain the widget's size when it is hidden.
+    If \a retainSize is \c true, the layout will not be changed by hiding the widget.
 
     \sa retainSizeWhenHidden()
 */
@@ -385,3 +428,72 @@
     \sa setControlType(), controlType()
 */
 
+/*!
+   Returns a QVariant storing this QSizePolicy.
+*/
+QSizePolicy::operator QVariant() const
+{
+    return QVariant(QVariant::SizePolicy, this);
+}
+
+#ifndef QT_NO_DATASTREAM
+
+/*!
+    \relates QSizePolicy
+    \since 4.2
+
+    Writes the size \a policy to the data stream \a stream.
+
+    \sa{Serializing Qt Data Types}{Format of the QDataStream operators}
+*/
+QDataStream &operator<<(QDataStream &stream, const QSizePolicy &policy)
+{
+    // The order here is for historical reasons. (compatibility with Qt4)
+    quint32 data = (policy.bits.horPolicy |         // [0, 3]
+                    policy.bits.verPolicy << 4 |    // [4, 7]
+                    policy.bits.hfw << 8 |          // [8]
+                    policy.bits.ctype << 9 |        // [9, 13]
+                    policy.bits.wfh << 14 |         // [14]
+                    policy.bits.retainSizeWhenHidden << 15 |     // [15]
+                    policy.bits.verStretch << 16 |  // [16, 23]
+                    policy.bits.horStretch << 24);  // [24, 31]
+    return stream << data;
+}
+
+#define VALUE_OF_BITS(data, bitstart, bitcount) ((data >> bitstart) & ((1 << bitcount) -1))
+
+/*!
+    \relates QSizePolicy
+    \since 4.2
+
+    Reads the size \a policy from the data stream \a stream.
+
+    \sa{Serializing Qt Data Types}{Format of the QDataStream operators}
+*/
+QDataStream &operator>>(QDataStream &stream, QSizePolicy &policy)
+{
+    quint32 data;
+    stream >> data;
+    policy.bits.horPolicy =  VALUE_OF_BITS(data, 0, 4);
+    policy.bits.verPolicy =  VALUE_OF_BITS(data, 4, 4);
+    policy.bits.hfw =        VALUE_OF_BITS(data, 8, 1);
+    policy.bits.ctype =      VALUE_OF_BITS(data, 9, 5);
+    policy.bits.wfh =        VALUE_OF_BITS(data, 14, 1);
+    policy.bits.retainSizeWhenHidden =    VALUE_OF_BITS(data, 15, 1);
+    policy.bits.verStretch = VALUE_OF_BITS(data, 16, 8);
+    policy.bits.horStretch = VALUE_OF_BITS(data, 24, 8);
+    return stream;
+}
+#endif // QT_NO_DATASTREAM
+
+#ifndef QT_NO_DEBUG_STREAM
+QDebug operator<<(QDebug dbg, const QSizePolicy &p)
+{
+    QDebugStateSaver saver(dbg);
+    dbg.nospace() << "QSizePolicy(horizontalPolicy = " << p.horizontalPolicy()
+                  << ", verticalPolicy = " << p.verticalPolicy() << ')';
+    return dbg;
+}
+#endif
+
+QT_END_NAMESPACE
diff --git a/src/widgets/kernel/qsizepolicy.h b/src/widgets/kernel/qsizepolicy.h
index 2376a2c644..6cd511f513 100644
--- a/src/widgets/kernel/qsizepolicy.h
+++ b/src/widgets/kernel/qsizepolicy.h
@@ -112,7 +112,7 @@ public:
 
     bool operator==(const QSizePolicy& s) const { return data == s.data; }
     bool operator!=(const QSizePolicy& s) const { return data != s.data; }
-    operator QVariant() const; // implemented in qlayoutitem.cpp
+    operator QVariant() const;
 
     int horizontalStretch() const { return static_cast<int>(bits.horStretch); }
     int verticalStretch() const { return static_cast<int>(bits.verStretch); }
@@ -155,7 +155,6 @@ Q_DECLARE_TYPEINFO(QSizePolicy, Q_PRIMITIVE_TYPE);
 Q_DECLARE_OPERATORS_FOR_FLAGS(QSizePolicy::ControlTypes)
 
 #ifndef QT_NO_DATASTREAM
-// implemented in qlayout.cpp
 Q_WIDGETS_EXPORT QDataStream &operator<<(QDataStream &, const QSizePolicy &);
 Q_WIDGETS_EXPORT QDataStream &operator>>(QDataStream &, QSizePolicy &);
 #endif
diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index f05094dd01..6e7479d29a 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -4860,7 +4860,7 @@ void QWidget::unsetLayoutDirection()
     \fn QFontMetrics QWidget::fontMetrics() const
 
     Returns the font metrics for the widget's current font.
-    Equivalent to QFontMetrics(widget->font()).
+    Equivalent to \c QFontMetrics(widget->font()).
 
     \sa font(), fontInfo(), setFont()
 */
@@ -4869,7 +4869,7 @@ void QWidget::unsetLayoutDirection()
     \fn QFontInfo QWidget::fontInfo() const
 
     Returns the font info for the widget's current font.
-    Equivalent to QFontInto(widget->font()).
+    Equivalent to \c QFontInfo(widget->font()).
 
     \sa font(), fontMetrics(), setFont()
 */
@@ -7335,6 +7335,8 @@ bool QWidget::restoreGeometry(const QByteArray &geometry)
         stream >> restoredScreenWidth;
 
     const QDesktopWidget * const desktop = QApplication::desktop();
+    if (restoredScreenNumber >= desktop->numScreens())
+        restoredScreenNumber = desktop->primaryScreen();
     const qreal screenWidthF = qreal(desktop->screenGeometry(restoredScreenNumber).width());
     // Sanity check bailing out when large variations of screen sizes occur due to
     // high DPI scaling or different levels of DPI awareness.
@@ -7362,9 +7364,6 @@ bool QWidget::restoreGeometry(const QByteArray &geometry)
                                        .expandedTo(d_func()->adjustedSize()));
     }
 
-    if (restoredScreenNumber >= desktop->numScreens())
-        restoredScreenNumber = desktop->primaryScreen();
-
     const QRect availableGeometry = desktop->availableGeometry(restoredScreenNumber);
 
     // Modify the restored geometry if we are about to restore to coordinates
@@ -12092,6 +12091,7 @@ QOpenGLContext *QWidgetPrivate::shareContext() const
         QOpenGLContext *ctx = new QOpenGLContext;
         ctx->setShareContext(qt_gl_global_share_context());
         ctx->setFormat(extra->topextra->window->format());
+        ctx->setScreen(extra->topextra->window->screen());
         ctx->create();
         that->extra->topextra->shareContext = ctx;
     }
diff --git a/src/widgets/kernel/qwidgetbackingstore.cpp b/src/widgets/kernel/qwidgetbackingstore.cpp
index 485cf82078..d1070839fa 100644
--- a/src/widgets/kernel/qwidgetbackingstore.cpp
+++ b/src/widgets/kernel/qwidgetbackingstore.cpp
@@ -962,7 +962,8 @@ static void findTextureWidgetsRecursively(QWidget *tlw, QWidget *widget, QPlatfo
         QPlatformTextureList::Flags flags = 0;
         if (widget->testAttribute(Qt::WA_AlwaysStackOnTop))
             flags |= QPlatformTextureList::StacksOnTop;
-        widgetTextures->appendTexture(widget, wd->textureId(), QRect(widget->mapTo(tlw, QPoint()), widget->size()), flags);
+        const QRect rect(widget->mapTo(tlw, QPoint()), widget->size());
+        widgetTextures->appendTexture(widget, wd->textureId(), rect, wd->clipRect(), flags);
     }
 
     for (int i = 0; i < wd->children.size(); ++i) {
@@ -1156,7 +1157,7 @@ void QWidgetBackingStore::doSync()
 #ifndef QT_NO_OPENGL
     if (widgetTextures && widgetTextures->count()) {
         for (int i = 0; i < widgetTextures->count(); ++i) {
-            QWidget *w = widgetTextures->widget(i);
+            QWidget *w = static_cast<QWidget *>(widgetTextures->source(i));
             if (dirtyRenderToTextureWidgets.contains(w)) {
                 const QRect rect = widgetTextures->geometry(i); // mapped to the tlw already
                 dirty += rect;
diff --git a/src/widgets/kernel/qwidgetwindow.cpp b/src/widgets/kernel/qwidgetwindow.cpp
index d8f89d279b..633e710853 100644
--- a/src/widgets/kernel/qwidgetwindow.cpp
+++ b/src/widgets/kernel/qwidgetwindow.cpp
@@ -52,7 +52,6 @@ QT_BEGIN_NAMESPACE
 Q_WIDGETS_EXPORT extern bool qt_tab_all_widgets();
 
 QWidget *qt_button_down = 0; // widget got last button-down
-static QPointer<QWidget> qt_tablet_target = 0;
 
 // popup control
 QWidget *qt_popup_down = 0; // popup that contains the pressed widget
@@ -447,8 +446,8 @@ void QWidgetWindow::handleMouseEvent(QMouseEvent *event)
             if (receiver != popup)
                 widgetPos = receiver->mapFromGlobal(event->globalPos());
             QWidget *alien = m_widget->childAt(m_widget->mapFromGlobal(event->globalPos()));
-            QMouseEvent e(event->type(), widgetPos, event->windowPos(), event->screenPos(), event->button(), event->buttons(), event->modifiers());
-            QGuiApplicationPrivate::setMouseEventSource(&e, QGuiApplicationPrivate::mouseEventSource(event));
+            QMouseEvent e(event->type(), widgetPos, event->windowPos(), event->screenPos(),
+                          event->button(), event->buttons(), event->modifiers(), event->source());
             e.setTimestamp(event->timestamp());
             QApplicationPrivate::sendMouseEvent(receiver, &e, alien, m_widget, &qt_button_down, qt_last_mouse_receiver);
             qt_last_mouse_receiver = receiver;
@@ -490,9 +489,9 @@ void QWidgetWindow::handleMouseEvent(QMouseEvent *event)
                         if (globalGeometry.contains(event->globalPos())) {
                             // Use postEvent() to ensure the local QEventLoop terminates when called from QMenu::exec()
                             const QPoint localPos = win->mapFromGlobal(event->globalPos());
-                            QMouseEvent *e = new QMouseEvent(QEvent::MouseButtonPress, localPos, localPos, event->globalPos(), event->button(), event->buttons(), event->modifiers());
+                            QMouseEvent *e = new QMouseEvent(QEvent::MouseButtonPress, localPos, localPos, event->globalPos(),
+                                                             event->button(), event->buttons(), event->modifiers(), event->source());
                             QCoreApplicationPrivate::setEventSpontaneous(e, true);
-                            QGuiApplicationPrivate::setMouseEventSource(e, QGuiApplicationPrivate::mouseEventSource(event));
                             e->setTimestamp(event->timestamp());
                             QCoreApplication::postEvent(win, e);
                         }
@@ -549,8 +548,7 @@ void QWidgetWindow::handleMouseEvent(QMouseEvent *event)
         // The preceding statement excludes MouseButtonPress events which caused
         // creation of a MouseButtonDblClick event. QTBUG-25831
         QMouseEvent translated(event->type(), mapped, event->windowPos(), event->screenPos(),
-                               event->button(), event->buttons(), event->modifiers());
-        QGuiApplicationPrivate::setMouseEventSource(&translated, QGuiApplicationPrivate::mouseEventSource(event));
+                               event->button(), event->buttons(), event->modifiers(), event->source());
         translated.setTimestamp(event->timestamp());
         QApplicationPrivate::sendMouseEvent(receiver, &translated, widget, m_widget,
                                             &qt_button_down, qt_last_mouse_receiver);
@@ -875,6 +873,7 @@ bool QWidgetWindow::nativeEvent(const QByteArray &eventType, void *message, long
 #ifndef QT_NO_TABLETEVENT
 void QWidgetWindow::handleTabletEvent(QTabletEvent *event)
 {
+    static QPointer<QWidget> qt_tablet_target = 0;
     if (event->type() == QEvent::TabletPress) {
         QWidget *widget = m_widget->childAt(event->pos());
         if (!widget)
diff --git a/src/widgets/styles/qcommonstylepixmaps_p.h b/src/widgets/styles/qcommonstylepixmaps_p.h
index 471903e927..8075256158 100644
--- a/src/widgets/styles/qcommonstylepixmaps_p.h
+++ b/src/widgets/styles/qcommonstylepixmaps_p.h
@@ -348,7 +348,7 @@ static const char * const qt_unshade_xpm[] = {
 "..........",
 ".........."};
 
-static const char * dock_widget_close_xpm[] = {
+static const char * const dock_widget_close_xpm[] = {
 "8 8 2 1",
 "# c #000000",
 ". c None",
diff --git a/src/widgets/styles/qmacstyle_mac.mm b/src/widgets/styles/qmacstyle_mac.mm
index 95a41b4830..518f985b13 100644
--- a/src/widgets/styles/qmacstyle_mac.mm
+++ b/src/widgets/styles/qmacstyle_mac.mm
@@ -93,18 +93,6 @@
 
 QT_USE_NAMESPACE
 
-namespace {
-class AutoReleasePool
-{
-public:
-    AutoReleasePool(): pool([[NSAutoreleasePool alloc] init]) {}
-    ~AutoReleasePool() { [pool release]; }
-
-private:
-    NSAutoreleasePool *pool;
-};
-}
-
 @interface QT_MANGLE_NAMESPACE(NotificationReceiver) : NSObject {
 QMacStylePrivate *mPrivate;
 }
@@ -1753,7 +1741,7 @@ QMacStylePrivate::QMacStylePrivate()
 
 QMacStylePrivate::~QMacStylePrivate()
 {
-    AutoReleasePool pool;
+    QMacAutoReleasePool pool;
     Q_FOREACH (NSView *b, cocoaControls)
         [b release];
 }
@@ -2135,7 +2123,7 @@ QMacStyle::QMacStyle()
     : QCommonStyle(*new QMacStylePrivate)
 {
     Q_D(QMacStyle);
-    AutoReleasePool pool;
+    QMacAutoReleasePool pool;
 
     d->receiver = [[NotificationReceiver alloc] initWithPrivate:d];
     NotificationReceiver *receiver = static_cast<NotificationReceiver *>(d->receiver);
@@ -2152,7 +2140,7 @@ QMacStyle::QMacStyle()
 QMacStyle::~QMacStyle()
 {
     Q_D(QMacStyle);
-    AutoReleasePool pool;
+    QMacAutoReleasePool pool;
 
     [reinterpret_cast<NSScroller*>(d->nsscroller) release];
 
@@ -2169,7 +2157,7 @@ QMacStyle::~QMacStyle()
 */
 QPixmap QMacStylePrivate::generateBackgroundPattern() const
 {
-    AutoReleasePool pool;
+    QMacAutoReleasePool pool;
     QPixmap px(4, 4);
     QMacCGContext cg(&px);
     HIThemeSetFill(kThemeBrushDialogBackgroundActive, 0, cg, kHIThemeOrientationNormal);
@@ -2767,7 +2755,7 @@ QPalette QMacStyle::standardPalette() const
 int QMacStyle::styleHint(StyleHint sh, const QStyleOption *opt, const QWidget *w,
                          QStyleHintReturn *hret) const
 {
-    AutoReleasePool pool;
+    QMacAutoReleasePool pool;
 
     SInt32 ret = 0;
     switch (sh) {
diff --git a/src/widgets/styles/qstyle.cpp b/src/widgets/styles/qstyle.cpp
index 862a4302f3..1849331b79 100644
--- a/src/widgets/styles/qstyle.cpp
+++ b/src/widgets/styles/qstyle.cpp
@@ -2368,8 +2368,8 @@ QDebug operator<<(QDebug debug, QStyle::State state)
     return operator<< <QStyle::StateFlag>(debug, state);
 #    else
     Q_UNUSED(state);
-#    endif
     return debug;
+#    endif
 }
 #  endif // !QT_NO_DEBUG_STREAM
 #endif // QT_VERSION < QT_VERSION_CHECK(6,0,0)
diff --git a/src/widgets/styles/qstylesheetstyle.cpp b/src/widgets/styles/qstylesheetstyle.cpp
index 86b5632d2e..40b8aaae9a 100644
--- a/src/widgets/styles/qstylesheetstyle.cpp
+++ b/src/widgets/styles/qstylesheetstyle.cpp
@@ -586,7 +586,7 @@ public:
 };
 
 ///////////////////////////////////////////////////////////////////////////////////////////
-static const char *knownStyleHints[] = {
+static const char *const knownStyleHints[] = {
     "activate-on-singleclick",
     "alignment",
     "arrow-keys-navigate-into-children",
diff --git a/src/widgets/styles/qwindowsstyle.cpp b/src/widgets/styles/qwindowsstyle.cpp
index 40597a41f3..db8a649931 100644
--- a/src/widgets/styles/qwindowsstyle.cpp
+++ b/src/widgets/styles/qwindowsstyle.cpp
@@ -299,8 +299,8 @@ void QWindowsStyle::polish(QPalette &pal)
 
 int QWindowsStylePrivate::pixelMetricFromSystemDp(QStyle::PixelMetric pm, const QStyleOption *, const QWidget *widget)
 {
-    switch (pm) {
 #if defined(Q_OS_WIN) && !defined(Q_OS_WINRT)
+    switch (pm) {
     case QStyle::PM_DockWidgetFrameWidth:
 #  ifndef Q_OS_WINCE
         return GetSystemMetrics(SM_CXFRAME);
@@ -337,13 +337,14 @@ int QWindowsStylePrivate::pixelMetricFromSystemDp(QStyle::PixelMetric pm, const
 #  else
         return GetSystemMetrics(SM_CYDLGFRAME);
 #  endif
-#else
-    Q_UNUSED(widget)
-#endif // Q_OS_WIN
 
     default:
         break;
     }
+#else // Q_OS_WIN && !Q_OS_WINRT
+    Q_UNUSED(pm);
+    Q_UNUSED(widget);
+#endif
     return QWindowsStylePrivate::InvalidMetric;
 }
 
diff --git a/src/widgets/styles/qwindowsvistastyle.cpp b/src/widgets/styles/qwindowsvistastyle.cpp
index f715d93298..daa8ab12a9 100644
--- a/src/widgets/styles/qwindowsvistastyle.cpp
+++ b/src/widgets/styles/qwindowsvistastyle.cpp
@@ -250,8 +250,6 @@ void QWindowsVistaStyle::drawPrimitive(PrimitiveElement element, const QStyleOpt
 
     int state = option->state;
     if (!QWindowsVistaStylePrivate::useVista()) {
-        foreach (const QObject *target, d->animationTargets())
-            d->stopAnimation(target);
         QWindowsStyle::drawPrimitive(element, option, painter, widget);
         return;
     }
@@ -810,8 +808,6 @@ void QWindowsVistaStyle::drawControl(ControlElement element, const QStyleOption
     QWindowsVistaStylePrivate *d = const_cast<QWindowsVistaStylePrivate*>(d_func());
 
     if (!QWindowsVistaStylePrivate::useVista()) {
-        foreach (const QObject *target, d->animationTargets())
-            d->stopAnimation(target);
         QWindowsStyle::drawControl(element, option, painter, widget);
         return;
     }
@@ -1494,8 +1490,6 @@ void QWindowsVistaStyle::drawComplexControl(ComplexControl control, const QStyle
 {
     QWindowsVistaStylePrivate *d = const_cast<QWindowsVistaStylePrivate*>(d_func());
     if (!QWindowsVistaStylePrivate::useVista()) {
-        foreach (const QObject *target, d->animationTargets())
-            d->stopAnimation(target);
         QWindowsStyle::drawComplexControl(control, option, painter, widget);
         return;
     }
diff --git a/src/widgets/util/qflickgesture.cpp b/src/widgets/util/qflickgesture.cpp
index 0e598717c8..8eadc42625 100644
--- a/src/widgets/util/qflickgesture.cpp
+++ b/src/widgets/util/qflickgesture.cpp
@@ -66,8 +66,8 @@ static QMouseEvent *copyMouseEvent(QEvent *e)
     case QEvent::MouseButtonRelease:
     case QEvent::MouseMove: {
         QMouseEvent *me = static_cast<QMouseEvent *>(e);
-        QMouseEvent *cme = new QMouseEvent(me->type(), QPoint(0, 0), me->windowPos(), me->screenPos(), me->button(), me->buttons(), me->modifiers());
-        QGuiApplicationPrivate::setMouseEventSource(cme, me->source());
+        QMouseEvent *cme = new QMouseEvent(me->type(), QPoint(0, 0), me->windowPos(), me->screenPos(),
+                                           me->button(), me->buttons(), me->modifiers(), me->source());
         return cme;
     }
 #ifndef QT_NO_GRAPHICSVIEW
@@ -78,8 +78,8 @@ static QMouseEvent *copyMouseEvent(QEvent *e)
 #if 1
         QEvent::Type met = me->type() == QEvent::GraphicsSceneMousePress ? QEvent::MouseButtonPress :
                            (me->type() == QEvent::GraphicsSceneMouseRelease ? QEvent::MouseButtonRelease : QEvent::MouseMove);
-        QMouseEvent *cme = new QMouseEvent(met, QPoint(0, 0), QPoint(0, 0), me->screenPos(), me->button(), me->buttons(), me->modifiers());
-        QGuiApplicationPrivate::setMouseEventSource(cme, me->source());
+        QMouseEvent *cme = new QMouseEvent(met, QPoint(0, 0), QPoint(0, 0), me->screenPos(),
+                                           me->button(), me->buttons(), me->modifiers(), me->source());
         return cme;
 #else
         QGraphicsSceneMouseEvent *copy = new QGraphicsSceneMouseEvent(me->type());
@@ -240,8 +240,7 @@ public:
             qFGDebug() << "QFG: sending a fake mouse release at far-far-away to " << mouseTarget;
             QMouseEvent re(QEvent::MouseButtonRelease, QPoint(), farFarAway, farFarAway,
                            mouseButton, QApplication::mouseButtons() & ~mouseButton,
-                           QApplication::keyboardModifiers());
-            QGuiApplicationPrivate::setMouseEventSource(&re, mouseEventSource);
+                           QApplication::keyboardModifiers(), mouseEventSource);
             sendMouseEvent(&re, RegrabMouseAfterwards);
             // don't clear the mouseTarget just yet, since we need to explicitly ungrab the mouse on release!
         }
@@ -291,8 +290,7 @@ protected:
             if (me) {
                 QMouseEvent copy(me->type(), mouseTarget->mapFromGlobal(me->globalPos()),
                                  mouseTarget->topLevelWidget()->mapFromGlobal(me->globalPos()), me->screenPos(),
-                                 me->button(), me->buttons(), me->modifiers());
-                QGuiApplicationPrivate::setMouseEventSource(&copy, me->source());
+                                 me->button(), me->buttons(), me->modifiers(), me->source());
                 qt_sendSpontaneousEvent(mouseTarget, &copy);
             }
 
diff --git a/src/widgets/util/qscroller_mac.mm b/src/widgets/util/qscroller_mac.mm
index 9120c43075..07de07de52 100644
--- a/src/widgets/util/qscroller_mac.mm
+++ b/src/widgets/util/qscroller_mac.mm
@@ -43,7 +43,7 @@ QT_BEGIN_NAMESPACE
 
 QPointF QScrollerPrivate::realDpi(int screen)
 {
-    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+    QMacAutoReleasePool pool;
     NSArray *nsscreens = [NSScreen screens];
 
     if (screen < 0 || screen >= int([nsscreens count]))
@@ -59,7 +59,6 @@ QPointF QScrollerPrivate::realDpi(int screen)
     } else {
         return QPointF();
     }
-    [pool release];
 }
 
 QT_END_NAMESPACE
diff --git a/src/widgets/widgets/qabstractscrollarea.cpp b/src/widgets/widgets/qabstractscrollarea.cpp
index 2e1caedde7..5e45c66f3b 100644
--- a/src/widgets/widgets/qabstractscrollarea.cpp
+++ b/src/widgets/widgets/qabstractscrollarea.cpp
@@ -168,6 +168,10 @@ QAbstractScrollAreaPrivate::QAbstractScrollAreaPrivate()
 {
 }
 
+QAbstractScrollAreaPrivate::~QAbstractScrollAreaPrivate()
+{
+}
+
 QAbstractScrollAreaScrollBarContainer::QAbstractScrollAreaScrollBarContainer(Qt::Orientation orientation, QWidget *parent)
     :QWidget(parent), scrollBar(new QScrollBar(orientation, this)),
      layout(new QBoxLayout(orientation == Qt::Horizontal ? QBoxLayout::LeftToRight : QBoxLayout::TopToBottom)),
diff --git a/src/widgets/widgets/qabstractscrollarea_p.h b/src/widgets/widgets/qabstractscrollarea_p.h
index f770bb69f8..33222573f4 100644
--- a/src/widgets/widgets/qabstractscrollarea_p.h
+++ b/src/widgets/widgets/qabstractscrollarea_p.h
@@ -54,12 +54,15 @@ QT_BEGIN_NAMESPACE
 
 class QScrollBar;
 class QAbstractScrollAreaScrollBarContainer;
+
+// ### Qt 6: is the export still needed? If not, unexport QFramePrivate, too.
 class Q_WIDGETS_EXPORT QAbstractScrollAreaPrivate: public QFramePrivate
 {
     Q_DECLARE_PUBLIC(QAbstractScrollArea)
 
 public:
     QAbstractScrollAreaPrivate();
+    ~QAbstractScrollAreaPrivate();
 
     void replaceScrollBar(QScrollBar *scrollBar, Qt::Orientation orientation);
 
diff --git a/src/widgets/widgets/qcombobox.cpp b/src/widgets/widgets/qcombobox.cpp
index 76f923904d..ef80e359df 100644
--- a/src/widgets/widgets/qcombobox.cpp
+++ b/src/widgets/widgets/qcombobox.cpp
@@ -3034,7 +3034,7 @@ void QComboBoxPrivate::showPopupFromMouseEvent(QMouseEvent *e)
     QStyle::SubControl sc = q->style()->hitTestComplexControl(QStyle::CC_ComboBox, &opt, e->pos(), q);
 
     if (e->button() == Qt::LeftButton
-            && sc != QStyle::SC_None
+            && !(sc == QStyle::SC_None && e->type() == QEvent::MouseButtonRelease)
             && (sc == QStyle::SC_ComboBoxArrow || !q->isEditable())
             && !viewContainer()->isVisible()) {
         if (sc == QStyle::SC_ComboBoxArrow)
diff --git a/src/widgets/widgets/qdatetimeedit.cpp b/src/widgets/widgets/qdatetimeedit.cpp
index b1749fa5d3..a8da78a025 100644
--- a/src/widgets/widgets/qdatetimeedit.cpp
+++ b/src/widgets/widgets/qdatetimeedit.cpp
@@ -2316,9 +2316,9 @@ void QDateTimeEdit::paintEvent(QPaintEvent *event)
 QString QDateTimeEditPrivate::getAmPmText(AmPm ap, Case cs) const
 {
     if (ap == AmText) {
-        return (cs == UpperCase ? QDateTimeEdit::tr("AM") : QDateTimeEdit::tr("am"));
+        return (cs == UpperCase ? QDateTimeParser::tr("AM") : QDateTimeParser::tr("am"));
     } else {
-        return (cs == UpperCase ? QDateTimeEdit::tr("PM") : QDateTimeEdit::tr("pm"));
+        return (cs == UpperCase ? QDateTimeParser::tr("PM") : QDateTimeParser::tr("pm"));
     }
 }
 
diff --git a/src/widgets/widgets/qdialogbuttonbox.cpp b/src/widgets/widgets/qdialogbuttonbox.cpp
index 237eb775b9..3e8c08f923 100644
--- a/src/widgets/widgets/qdialogbuttonbox.cpp
+++ b/src/widgets/widgets/qdialogbuttonbox.cpp
@@ -852,9 +852,19 @@ void QDialogButtonBoxPrivate::_q_handleButtonClicked()
 {
     Q_Q(QDialogButtonBox);
     if (QAbstractButton *button = qobject_cast<QAbstractButton *>(q->sender())) {
+        // Can't fetch this *after* emitting clicked, as clicked may destroy the button
+        // or change its role. Now changing the role is not possible yet, but arguably
+        // both clicked and accepted/rejected/etc. should be emitted "atomically"
+        // depending on whatever role the button had at the time of the click.
+        const QDialogButtonBox::ButtonRole buttonRole = q->buttonRole(button);
+        QPointer<QDialogButtonBox> guard(q);
+
         emit q->clicked(button);
 
-        switch (q->buttonRole(button)) {
+        if (!guard)
+            return;
+
+        switch (buttonRole) {
         case QPlatformDialogHelper::AcceptRole:
         case QPlatformDialogHelper::YesRole:
             emit q->accepted();
diff --git a/src/widgets/widgets/qdockarealayout.cpp b/src/widgets/widgets/qdockarealayout.cpp
index af0f2515fe..bc2259ce90 100644
--- a/src/widgets/widgets/qdockarealayout.cpp
+++ b/src/widgets/widgets/qdockarealayout.cpp
@@ -1,6 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2015 The Qt Company Ltd.
+** Copyright (C) 2015 Olivier Goffart <ogoffart@woboq.com>
 ** Contact: http://www.qt.io/licensing/
 **
 ** This file is part of the QtWidgets module of the Qt Toolkit.
@@ -1854,20 +1855,6 @@ static Qt::DockWidgetArea toDockWidgetArea(QInternal::DockPosition pos)
     return Qt::NoDockWidgetArea;
 }
 
-static QRect constrainedRect(QRect rect, const QRect &desktop)
-{
-    if (desktop.isValid()) {
-        rect.setWidth(qMin(rect.width(), desktop.width()));
-        rect.setHeight(qMin(rect.height(), desktop.height()));
-        rect.moveLeft(qMax(rect.left(), desktop.left()));
-        rect.moveTop(qMax(rect.top(), desktop.top()));
-        rect.moveRight(qMin(rect.right(), desktop.right()));
-        rect.moveBottom(qMin(rect.bottom(), desktop.bottom()));
-    }
-
-    return rect;
-}
-
 bool QDockAreaLayoutInfo::restoreState(QDataStream &stream, QList<QDockWidget*> &widgets, bool testing)
 {
     uchar marker;
@@ -1958,11 +1945,7 @@ bool QDockAreaLayoutInfo::restoreState(QDataStream &stream, QList<QDockWidget*>
 #endif
                     if (!testing) {
                         QRect r(x, y, w, h);
-                        QDesktopWidget *desktop = QApplication::desktop();
-                        if (desktop->isVirtualDesktop())
-                            r = constrainedRect(r, desktop->screenGeometry(desktop->screenNumber(r.topLeft())));
-                        else
-                            r = constrainedRect(r, desktop->screenGeometry(widget));
+                        r = QDockAreaLayout::constrainedRect(r, widget);
                         widget->move(r.topLeft());
                         widget->resize(r.size());
                     }
@@ -2075,6 +2058,36 @@ void QDockAreaLayoutInfo::updateSeparatorWidgets() const
 #endif //QT_NO_TABBAR
 
 #ifndef QT_NO_TABBAR
+/*! \internal
+    reparent all the widgets contained in this layout portion to the
+    specified parent. This is used to reparent dock widgets and tabbars
+    to the floating window or the main window
+ */
+void QDockAreaLayoutInfo::reparentWidgets(QWidget *parent)
+{
+    if (tabBar)
+        tabBar->setParent(parent);
+
+    for (int i = 0; i < item_list.count(); ++i) {
+        const QDockAreaLayoutItem &item = item_list.at(i);
+        if (item.flags & QDockAreaLayoutItem::GapItem)
+            continue;
+        if (item.skip())
+            continue;
+        if (item.subinfo)
+            item.subinfo->reparentWidgets(parent);
+        if (item.widgetItem) {
+            QWidget *w = item.widgetItem->widget();
+            if (w->parent() != parent) {
+                bool hidden = w->isHidden();
+                w->setParent(parent);
+                if (!hidden)
+                    w->show();
+            }
+        }
+    }
+}
+
 //returns whether the tabbar is visible or not
 bool QDockAreaLayoutInfo::updateTabBar() const
 {
@@ -2981,6 +2994,33 @@ QSize QDockAreaLayout::minimumSize() const
     return QSize(qMax(row1, row2, row3), qMax(col1, col2, col3));
 }
 
+/*! \internal
+    Try to fit the given rectangle \a rect on the screen which contains
+    the window \a widget.
+    Used to compute the geometry of a dragged a dock widget that should
+    be shown with \a rect, but needs to be visible on the screen
+ */
+QRect QDockAreaLayout::constrainedRect(QRect rect, QWidget* widget)
+{
+    QRect desktop;
+    QDesktopWidget *desktopW = QApplication::desktop();
+    if (desktopW->isVirtualDesktop())
+        desktop = desktopW->screenGeometry(rect.topLeft());
+    else
+        desktop = desktopW->screenGeometry(widget);
+
+    if (desktop.isValid()) {
+        rect.setWidth(qMin(rect.width(), desktop.width()));
+        rect.setHeight(qMin(rect.height(), desktop.height()));
+        rect.moveLeft(qMax(rect.left(), desktop.left()));
+        rect.moveTop(qMax(rect.top(), desktop.top()));
+        rect.moveRight(qMin(rect.right(), desktop.right()));
+        rect.moveBottom(qMin(rect.bottom(), desktop.bottom()));
+    }
+
+    return rect;
+}
+
 bool QDockAreaLayout::restoreDockWidget(QDockWidget *dockWidget)
 {
     QList<int> index = indexOfPlaceHolder(dockWidget->objectName());
@@ -2994,9 +3034,7 @@ bool QDockAreaLayout::restoreDockWidget(QDockWidget *dockWidget)
     item.widgetItem = new QDockWidgetItem(dockWidget);
 
     if (placeHolder->window) {
-        const QRect screenGeometry =
-            QApplication::desktop()->screenGeometry(placeHolder->topLevelRect.center());
-        const QRect r = constrainedRect(placeHolder->topLevelRect, screenGeometry);
+        const QRect r = constrainedRect(placeHolder->topLevelRect, dockWidget);
         dockWidget->d_func()->setWindowState(true, true, r);
     }
     dockWidget->setVisible(!placeHolder->hidden);
diff --git a/src/widgets/widgets/qdockarealayout_p.h b/src/widgets/widgets/qdockarealayout_p.h
index 64fae7ebf6..93b005f64f 100644
--- a/src/widgets/widgets/qdockarealayout_p.h
+++ b/src/widgets/widgets/qdockarealayout_p.h
@@ -202,6 +202,7 @@ public:
     QTabBar *tabBar;
     int tabBarShape;
 
+    void reparentWidgets(QWidget *p);
     bool updateTabBar() const;
     void setTabBarShape(int shape);
     QSize tabBarMinimumSize() const;
@@ -232,7 +233,8 @@ public:
 
     bool isValid() const;
 
-    enum { DockWidgetStateMarker = 0xfd };
+    enum { DockWidgetStateMarker = 0xfd, FloatingDockWidgetTabMarker = 0xf9 };
+    static QRect constrainedRect(QRect rect, QWidget *widget);
     void saveState(QDataStream &stream) const;
     bool restoreState(QDataStream &stream, const QList<QDockWidget*> &widgets, bool testing = false);
 
diff --git a/src/widgets/widgets/qdockwidget.cpp b/src/widgets/widgets/qdockwidget.cpp
index 21b0904cc0..1b7473fbd7 100644
--- a/src/widgets/widgets/qdockwidget.cpp
+++ b/src/widgets/widgets/qdockwidget.cpp
@@ -65,6 +65,18 @@ extern QString qt_setWindowTitle_helperHelper(const QString&, const QWidget*); /
 // qmainwindow.cpp
 extern QMainWindowLayout *qt_mainwindow_layout(const QMainWindow *window);
 
+static inline QMainWindowLayout *qt_mainwindow_layout_from_dock(const QDockWidget *dock)
+{
+    const QWidget *p = dock->parentWidget();
+    while (p) {
+        const QMainWindow *window = qobject_cast<const QMainWindow*>(p);
+        if (window)
+            return qt_mainwindow_layout(window);
+        p = p->parentWidget();
+    }
+    return Q_NULLPTR;
+}
+
 static inline bool hasFeature(const QDockWidgetPrivate *priv, QDockWidget::DockWidgetFeature feature)
 { return (priv->features & feature) == feature; }
 
@@ -194,25 +206,40 @@ QDockWidgetLayout::~QDockWidgetLayout()
     qDeleteAll(item_list);
 }
 
+/*! \internal
+    Returns true if the dock widget managed by this layout should have a native
+    window decoration or if Qt needs to draw it.
+ */
 bool QDockWidgetLayout::nativeWindowDeco() const
 {
-    return nativeWindowDeco(parentWidget()->isWindow());
+    bool floating = parentWidget()->isWindow();
+    if (!floating && qobject_cast<QDockWidgetGroupWindow*>(parentWidget()->parentWidget()))
+        return wmSupportsNativeWindowDeco();
+    return nativeWindowDeco(floating);
 }
 
-static bool isXcb()
+/*! \internal
+    Returns true if the window manager can draw natively the windows decoration
+    of a dock widget
+ */
+bool QDockWidgetLayout::wmSupportsNativeWindowDeco()
 {
+#if defined(Q_OS_WINCE) || defined(Q_OS_ANDROID)
+    return false;
+#else
     static const bool xcb = !QGuiApplication::platformName().compare(QLatin1String("xcb"), Qt::CaseInsensitive);
-    return xcb;
+    return !xcb;
+#endif
 }
 
+/*! \internal
+   Returns true if the dock widget managed by this layout should have a native
+   window decoration or if Qt needs to draw it. The \a floating parameter
+   overrides the floating current state of the dock widget.
+ */
 bool QDockWidgetLayout::nativeWindowDeco(bool floating) const
 {
-#if defined(Q_OS_WINCE) || defined(Q_OS_ANDROID)
-    Q_UNUSED(floating)
-    return false;
-#else
-    return !isXcb() && (floating && item_list[QDockWidgetLayout::TitleBar] == 0);
-#endif
+    return wmSupportsNativeWindowDeco() && floating && item_list.at(QDockWidgetLayout::TitleBar) == 0;
 }
 
 
@@ -611,7 +638,10 @@ void QDockWidget::initStyleOption(QStyleOptionDockWidget *option) const
         return;
     QDockWidgetLayout *dwlayout = qobject_cast<QDockWidgetLayout*>(layout());
 
-    option->initFrom(this);
+    QDockWidgetGroupWindow *floatingTab = qobject_cast<QDockWidgetGroupWindow*>(parent());
+    // If we are in a floating tab, init from the parent because the attributes and the geometry
+    // of the title bar should be taken from the floating window.
+    option->initFrom(floatingTab && !isFloating() ? parentWidget() : this);
     option->rect = dwlayout->titleArea();
     option->title = d->fixedWindowTitle;
     option->closable = hasFeature(this, QDockWidget::DockWidgetClosable);
@@ -681,14 +711,20 @@ void QDockWidgetPrivate::_q_toggleTopLevel()
     q->setFloating(!q->isFloating());
 }
 
+/*! \internal
+    Initialize the drag state structure and remember the position of the click.
+    This is called when the mouse is pressed, but the dock is not yet dragged out.
+
+    \a nca specify that the event comes from NonClientAreaMouseButtonPress
+ */
 void QDockWidgetPrivate::initDrag(const QPoint &pos, bool nca)
 {
+    Q_Q(QDockWidget);
+
     if (state != 0)
         return;
 
-    QMainWindow *win = qobject_cast<QMainWindow*>(parent);
-    Q_ASSERT(win != 0);
-    QMainWindowLayout *layout = qt_mainwindow_layout(win);
+    QMainWindowLayout *layout = qt_mainwindow_layout_from_dock(q);
     Q_ASSERT(layout != 0);
     if (layout->pluggingWidget != 0) // the main window is animating a docking operation
         return;
@@ -702,17 +738,23 @@ void QDockWidgetPrivate::initDrag(const QPoint &pos, bool nca)
     state->ctrlDrag = false;
 }
 
-void QDockWidgetPrivate::startDrag()
+/*! \internal
+    Actually start the drag and detach the dockwidget.
+    The \a group parameter is true when we should potentially drag a group of
+    tabbed widgets, and false if the dock widget should always be dragged
+    alone.
+ */
+void QDockWidgetPrivate::startDrag(bool group)
 {
     Q_Q(QDockWidget);
 
     if (state == 0 || state->dragging)
         return;
 
-    QMainWindowLayout *layout = qt_mainwindow_layout(qobject_cast<QMainWindow *>(q->parentWidget()));
+    QMainWindowLayout *layout = qt_mainwindow_layout_from_dock(q);
     Q_ASSERT(layout != 0);
 
-    state->widgetItem = layout->unplug(q);
+    state->widgetItem = layout->unplug(q, group);
     if (state->widgetItem == 0) {
         /* I have a QMainWindow parent, but I was never inserted with
             QMainWindow::addDockWidget, so the QMainWindowLayout has no
@@ -728,6 +770,11 @@ void QDockWidgetPrivate::startDrag()
     state->dragging = true;
 }
 
+/*! \internal
+    Ends the drag end drop operation of the QDockWidget.
+    The \a abort parameter specifies that it ends because of programmatic state
+    reset rather than mouse release event.
+ */
 void QDockWidgetPrivate::endDrag(bool abort)
 {
     Q_Q(QDockWidget);
@@ -736,29 +783,31 @@ void QDockWidgetPrivate::endDrag(bool abort)
     q->releaseMouse();
 
     if (state->dragging) {
-        QMainWindowLayout *mwLayout = qt_mainwindow_layout(qobject_cast<QMainWindow *>(q->parentWidget()));
+        QMainWindowLayout *mwLayout = qt_mainwindow_layout_from_dock(q);
         Q_ASSERT(mwLayout != 0);
 
         if (abort || !mwLayout->plug(state->widgetItem)) {
             if (hasFeature(this, QDockWidget::DockWidgetFloatable)) {
+                // This QDockWidget will now stay in the floating state.
                 if (state->ownWidgetItem)
                     delete state->widgetItem;
                 mwLayout->restore();
-                if (isXcb()) {
+                QDockWidgetLayout *dwLayout = qobject_cast<QDockWidgetLayout*>(layout);
+                if (!dwLayout->nativeWindowDeco()) {
                     // get rid of the X11BypassWindowManager window flag and activate the resizer
                     Qt::WindowFlags flags = q->windowFlags();
                     flags &= ~Qt::X11BypassWindowManagerHint;
                     q->setWindowFlags(flags);
-                    setResizerActive(true);
+                    setResizerActive(q->isFloating());
                     q->show();
                 } else {
-                    QDockWidgetLayout *myLayout
-                            = qobject_cast<QDockWidgetLayout*>(layout);
-                    setResizerActive(myLayout->widgetForRole(QDockWidgetLayout::TitleBar) != 0);
+                    setResizerActive(false);
                 }
                 undockedGeometry = q->geometry();
                 q->activateWindow();
             } else {
+                // The tab was not plugged back in the QMainWindow but the QDockWidget cannot
+                // stay floating, revert to the previous state.
                 mwLayout->revert(state->widgetItem);
             }
         }
@@ -782,11 +831,7 @@ bool QDockWidgetPrivate::isAnimating() const
 {
     Q_Q(const QDockWidget);
 
-    QMainWindow *mainWin = qobject_cast<QMainWindow*>(parent);
-    if (mainWin == 0)
-        return false;
-
-    QMainWindowLayout *mainWinLayout = qt_mainwindow_layout(mainWin);
+    QMainWindowLayout *mainWinLayout = qt_mainwindow_layout_from_dock(q);
     if (mainWinLayout == 0)
         return false;
 
@@ -804,12 +849,14 @@ bool QDockWidgetPrivate::mousePressEvent(QMouseEvent *event)
     if (!dwLayout->nativeWindowDeco()) {
         QRect titleArea = dwLayout->titleArea();
 
+        QDockWidgetGroupWindow *floatingTab = qobject_cast<QDockWidgetGroupWindow*>(parent);
+
         if (event->button() != Qt::LeftButton ||
             !titleArea.contains(event->pos()) ||
             // check if the tool window is movable... do nothing if it
             // is not (but allow moving if the window is floating)
             (!hasFeature(this, QDockWidget::DockWidgetMovable) && !q->isFloating()) ||
-            qobject_cast<QMainWindow*>(parent) == 0 ||
+            (qobject_cast<QMainWindow*>(parent) == 0 && !floatingTab) ||
             isAnimating() || state != 0) {
             return false;
         }
@@ -853,7 +900,7 @@ bool QDockWidgetPrivate::mouseMoveEvent(QMouseEvent *event)
 
     QDockWidgetLayout *dwlayout
         = qobject_cast<QDockWidgetLayout *>(layout);
-    QMainWindowLayout *mwlayout = qt_mainwindow_layout(qobject_cast<QMainWindow *>(q->parentWidget()));
+    QMainWindowLayout *mwlayout = qt_mainwindow_layout_from_dock(q);
     if (!dwlayout->nativeWindowDeco()) {
         if (!state->dragging
             && mwlayout->pluggingWidget == 0
@@ -871,7 +918,12 @@ bool QDockWidgetPrivate::mouseMoveEvent(QMouseEvent *event)
 
     if (state->dragging && !state->nca) {
         QPoint pos = event->globalPos() - state->pressPos;
-        q->move(pos);
+
+        QDockWidgetGroupWindow *floatingTab = qobject_cast<QDockWidgetGroupWindow*>(parent);
+        if (floatingTab && !q->isFloating())
+            floatingTab->move(pos);
+        else
+            q->move(pos);
 
         if (state && !state->ctrlDrag)
             mwlayout->hover(state->widgetItem, event->globalPos());
@@ -902,8 +954,9 @@ void QDockWidgetPrivate::nonClientAreaMouseEvent(QMouseEvent *event)
 
     int fw = q->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, 0, q);
 
-    QRect geo = q->geometry();
-    QRect titleRect = q->frameGeometry();
+    QWidget *tl = q->topLevelWidget();
+    QRect geo = tl->geometry();
+    QRect titleRect = tl->frameGeometry();
 #ifdef Q_DEAD_CODE_FROM_QT4_MAC
     if ((features & QDockWidget::DockWidgetVerticalTitleBar)) {
         titleRect.setTop(geo.top());
@@ -924,7 +977,7 @@ void QDockWidgetPrivate::nonClientAreaMouseEvent(QMouseEvent *event)
                 break;
             if (state != 0)
                 break;
-            if (qobject_cast<QMainWindow*>(parent) == 0)
+            if (qobject_cast<QMainWindow*>(parent) == 0 && qobject_cast<QDockWidgetGroupWindow*>(parent) == 0)
                 break;
             if (isAnimating())
                 break;
@@ -958,11 +1011,17 @@ void QDockWidgetPrivate::nonClientAreaMouseEvent(QMouseEvent *event)
     }
 }
 
+/*! \internal
+    Called when the QDockWidget or the QDockWidgetGroupWindow is moved
+ */
 void QDockWidgetPrivate::moveEvent(QMoveEvent *event)
 {
     Q_Q(QDockWidget);
 
-    if (state == 0 || !state->dragging || !state->nca || !q->isWindow())
+    if (state == 0 || !state->dragging || !state->nca)
+        return;
+
+    if (!q->isWindow() && qobject_cast<QDockWidgetGroupWindow*>(parent) == 0)
         return;
 
     // When the native window frame is being dragged, all we get is these mouse
@@ -971,7 +1030,7 @@ void QDockWidgetPrivate::moveEvent(QMoveEvent *event)
     if (state->ctrlDrag)
         return;
 
-    QMainWindowLayout *layout = qt_mainwindow_layout(qobject_cast<QMainWindow *>(q->parentWidget()));
+    QMainWindowLayout *layout = qt_mainwindow_layout_from_dock(q);
     Q_ASSERT(layout != 0);
 
     QPoint globalMousePos = event->pos() + state->pressPos;
@@ -999,8 +1058,9 @@ void QDockWidgetPrivate::setWindowState(bool floating, bool unplug, const QRect
     Q_Q(QDockWidget);
 
     if (!floating && parent) {
-        QMainWindowLayout *mwlayout = qt_mainwindow_layout(qobject_cast<QMainWindow *>(q->parentWidget()));
-        if (mwlayout && mwlayout->dockWidgetArea(q) == Qt::NoDockWidgetArea)
+        QMainWindowLayout *mwlayout = qt_mainwindow_layout_from_dock(q);
+        if (mwlayout && mwlayout->dockWidgetArea(q) == Qt::NoDockWidgetArea
+                && !qobject_cast<QDockWidgetGroupWindow *>(parent))
             return; // this dockwidget can't be redocked
     }
 
@@ -1048,7 +1108,7 @@ void QDockWidgetPrivate::setWindowState(bool floating, bool unplug, const QRect
     if (floating != wasFloating) {
         emit q->topLevelChanged(floating);
         if (!floating && parent) {
-            QMainWindowLayout *mwlayout = qt_mainwindow_layout(qobject_cast<QMainWindow *>(q->parentWidget()));
+            QMainWindowLayout *mwlayout = qt_mainwindow_layout_from_dock(q);
             if (mwlayout)
                 emit q->dockLocationChanged(mwlayout->dockWidgetArea(q));
         }
@@ -1230,8 +1290,11 @@ void QDockWidget::setFeatures(QDockWidget::DockWidgetFeatures features)
     emit featuresChanged(d->features);
     update();
     if (closableChanged && layout->nativeWindowDeco()) {
-        //this ensures the native decoration is drawn
-        d->setWindowState(true /*floating*/, true /*unplug*/);
+        QDockWidgetGroupWindow *floatingTab = qobject_cast<QDockWidgetGroupWindow *>(parent());
+        if (floatingTab && !isFloating())
+            floatingTab->adjustFlags();
+        else
+            d->setWindowState(true /*floating*/, true /*unplug*/);  //this ensures the native decoration is drawn
     }
 }
 
@@ -1323,11 +1386,12 @@ void QDockWidget::changeEvent(QEvent *event)
 #endif
 #ifndef QT_NO_TABBAR
         {
-            QMainWindow *win = qobject_cast<QMainWindow*>(parentWidget());
-            if (QMainWindowLayout *winLayout = qt_mainwindow_layout(win)) {
+            if (QMainWindowLayout *winLayout = qt_mainwindow_layout_from_dock(this)) {
                 if (QDockAreaLayoutInfo *info = winLayout->layoutState.dockAreaLayout.info(this))
                     info->updateTabBar();
             }
+            if (QDockWidgetGroupWindow *p = qobject_cast<QDockWidgetGroupWindow *>(parent()))
+                p->adjustFlags();
         }
 #endif // QT_NO_TABBAR
         break;
@@ -1380,7 +1444,7 @@ bool QDockWidget::event(QEvent *event)
     Q_D(QDockWidget);
 
     QMainWindow *win = qobject_cast<QMainWindow*>(parentWidget());
-    QMainWindowLayout *layout = qt_mainwindow_layout(win);
+    QMainWindowLayout *layout = qt_mainwindow_layout_from_dock(this);
 
     switch (event->type()) {
 #ifndef QT_NO_ACTION
@@ -1417,6 +1481,9 @@ bool QDockWidget::event(QEvent *event)
         }
         if (!isFloating() && layout != 0 && onTop)
             layout->raise(this);
+        if (QDockWidgetGroupWindow *p = qobject_cast<QDockWidgetGroupWindow *>(parent()))
+            p->adjustFlags();
+
         break;
     }
     case QEvent::WindowActivate:
diff --git a/src/widgets/widgets/qdockwidget_p.h b/src/widgets/widgets/qdockwidget_p.h
index 752d6519e5..9c68bc5fb1 100644
--- a/src/widgets/widgets/qdockwidget_p.h
+++ b/src/widgets/widgets/qdockwidget_p.h
@@ -108,7 +108,7 @@ public:
     void setWindowState(bool floating, bool unplug = false, const QRect &rect = QRect());
     void nonClientAreaMouseEvent(QMouseEvent *event);
     void initDrag(const QPoint &pos, bool nca);
-    void startDrag();
+    void startDrag(bool group = true);
     void endDrag(bool abort = false);
     void moveEvent(QMoveEvent *event);
 
@@ -151,6 +151,7 @@ public:
     int minimumTitleWidth() const;
     int titleHeight() const;
     void updateMaxSize();
+    static bool wmSupportsNativeWindowDeco();
     bool nativeWindowDeco() const;
     bool nativeWindowDeco(bool floating) const;
 
diff --git a/src/widgets/widgets/qframe.cpp b/src/widgets/widgets/qframe.cpp
index 0861ea70b5..755b03a4ca 100644
--- a/src/widgets/widgets/qframe.cpp
+++ b/src/widgets/widgets/qframe.cpp
@@ -45,7 +45,7 @@
 QT_BEGIN_NAMESPACE
 
 QFramePrivate::QFramePrivate()
-    : frect(QRect(0, 0, 0, 0)),
+    : frect(0, 0, 0, 0),
       frameStyle(QFrame::NoFrame | QFrame::Plain),
       lineWidth(1),
       midLineWidth(0),
@@ -55,6 +55,10 @@ QFramePrivate::QFramePrivate()
 {
 }
 
+QFramePrivate::~QFramePrivate()
+{
+}
+
 inline void QFramePrivate::init()
 {
     setLayoutItemMargins(QStyle::SE_FrameLayoutItem);
diff --git a/src/widgets/widgets/qframe_p.h b/src/widgets/widgets/qframe_p.h
index 2b80e9abbe..eb04bbed4a 100644
--- a/src/widgets/widgets/qframe_p.h
+++ b/src/widgets/widgets/qframe_p.h
@@ -50,11 +50,13 @@
 
 QT_BEGIN_NAMESPACE
 
-class QFramePrivate : public QWidgetPrivate
+// ### unexport this class when and if QAbstractScrollAreaPrivate is unexported
+class Q_WIDGETS_EXPORT QFramePrivate : public QWidgetPrivate
 {
     Q_DECLARE_PUBLIC(QFrame)
 public:
     QFramePrivate();
+    ~QFramePrivate();
 
     void        updateFrameWidth();
     void        updateStyledFrameWidths();
diff --git a/src/widgets/widgets/qlabel.cpp b/src/widgets/widgets/qlabel.cpp
index fa1a5acb5f..c70bc4baef 100644
--- a/src/widgets/widgets/qlabel.cpp
+++ b/src/widgets/widgets/qlabel.cpp
@@ -53,6 +53,10 @@
 
 QT_BEGIN_NAMESPACE
 
+QLabelPrivate::~QLabelPrivate()
+{
+}
+
 /*!
     \class QLabel
     \brief The QLabel widget provides a text or image display.
diff --git a/src/widgets/widgets/qlabel_p.h b/src/widgets/widgets/qlabel_p.h
index 3778cb9d47..2eb4ff9fc6 100644
--- a/src/widgets/widgets/qlabel_p.h
+++ b/src/widgets/widgets/qlabel_p.h
@@ -65,6 +65,7 @@ class QLabelPrivate : public QFramePrivate
     Q_DECLARE_PUBLIC(QLabel)
 public:
     QLabelPrivate() {}
+    ~QLabelPrivate();
 
     void init();
     void clearContents();
diff --git a/src/widgets/widgets/qlineedit_p.cpp b/src/widgets/widgets/qlineedit_p.cpp
index 6a41c3791f..ad3a92d35a 100644
--- a/src/widgets/widgets/qlineedit_p.cpp
+++ b/src/widgets/widgets/qlineedit_p.cpp
@@ -440,6 +440,10 @@ QWidget *QLineEditPrivate::addAction(QAction *newAction, QAction *before, QLineE
     Q_Q(QLineEdit);
     if (!newAction)
         return 0;
+    if (!hasSideWidgets()) { // initial setup.
+        QObject::connect(q, SIGNAL(textChanged(QString)), q, SLOT(_q_textChanged(QString)));
+        lastTextSize = q->text().size();
+    }
     QWidget *w = 0;
     // Store flags about QWidgetAction here since removeAction() may be called from ~QAction,
     // in which a qobject_cast<> no longer works.
@@ -456,10 +460,6 @@ QWidget *QLineEditPrivate::addAction(QAction *newAction, QAction *before, QLineE
         toolButton->setDefaultAction(newAction);
         w = toolButton;
     }
-    if (!hasSideWidgets()) { // initial setup.
-        QObject::connect(q, SIGNAL(textChanged(QString)), q, SLOT(_q_textChanged(QString)));
-        lastTextSize = q->text().size();
-    }
     // If there is a 'before' action, it takes preference
     PositionIndexPair positionIndex = before ? findSideWidget(before) : PositionIndexPair(position, -1);
     SideWidgetEntryList &list = positionIndex.first == QLineEdit::TrailingPosition ? trailingSideWidgets : leadingSideWidgets;
diff --git a/src/widgets/widgets/qlineedit_p.h b/src/widgets/widgets/qlineedit_p.h
index 1ede07e4cb..4654262ea7 100644
--- a/src/widgets/widgets/qlineedit_p.h
+++ b/src/widgets/widgets/qlineedit_p.h
@@ -65,7 +65,7 @@ QT_BEGIN_NAMESPACE
 
 // QLineEditIconButton: This is a simple helper class that represents clickable icons that fade in with text
 
-class QLineEditIconButton : public QToolButton
+class Q_AUTOTEST_EXPORT QLineEditIconButton : public QToolButton
 {
     Q_OBJECT
     Q_PROPERTY(qreal opacity READ opacity WRITE setOpacity)
diff --git a/src/widgets/widgets/qmacnativewidget_mac.h b/src/widgets/widgets/qmacnativewidget_mac.h
index b27d877e8f..761e55656b 100644
--- a/src/widgets/widgets/qmacnativewidget_mac.h
+++ b/src/widgets/widgets/qmacnativewidget_mac.h
@@ -52,7 +52,6 @@ public:
     NSView *nativeView() const;
 
 protected:
-    void init(NSView *parentView);
     bool event(QEvent *ev);
 
 private:
diff --git a/src/widgets/widgets/qmainwindow.cpp b/src/widgets/widgets/qmainwindow.cpp
index 2a1e8428ab..f365ff7d17 100644
--- a/src/widgets/widgets/qmainwindow.cpp
+++ b/src/widgets/widgets/qmainwindow.cpp
@@ -420,6 +420,13 @@ QMainWindow::~QMainWindow()
                             at the bottom. Implies AllowTabbedDocks. See also
                             \l setTabPosition().
 
+    \value GroupedDragging  When dragging the titlebar of a dock, all the tabs
+                            that are tabbed with it are going to be dragged.
+                            Implies AllowTabbedDocks. Does not work well if
+                            some QDockWidgets have restrictions in which area
+                            they are allowed. (This enum value was added in Qt
+                            5.6.)
+
     These options only control how dock widgets may be dropped in a QMainWindow.
     They do not re-arrange the dock widgets to conform with the specified
     options. For this reason they should be set before any dock widgets
@@ -1080,7 +1087,7 @@ void QMainWindow::addDockWidget(Qt::DockWidgetArea area, QDockWidget *dockwidget
     addDockWidget(area, dockwidget, orientation);
 
 #ifdef Q_DEAD_CODE_FROM_QT4_MAC     //drawer support
-    QMacCocoaAutoReleasePool pool;
+    QMacAutoReleasePool pool;
     extern bool qt_mac_is_macdrawer(const QWidget *); //qwidget_mac.cpp
     if (qt_mac_is_macdrawer(dockwidget)) {
         extern bool qt_mac_set_drawer_preferred_edge(QWidget *, Qt::DockWidgetArea); //qwidget_mac.cpp
diff --git a/src/widgets/widgets/qmainwindow.h b/src/widgets/widgets/qmainwindow.h
index cbbea74b9b..0bd70c87a6 100644
--- a/src/widgets/widgets/qmainwindow.h
+++ b/src/widgets/widgets/qmainwindow.h
@@ -77,7 +77,8 @@ public:
         AllowNestedDocks = 0x02,
         AllowTabbedDocks = 0x04,
         ForceTabbedDocks = 0x08,  // implies AllowTabbedDocks, !AllowNestedDocks
-        VerticalTabs = 0x10       // implies AllowTabbedDocks
+        VerticalTabs = 0x10,      // implies AllowTabbedDocks
+        GroupedDragging = 0x20    // implies AllowTabbedDocks
     };
     Q_ENUM(DockOption)
     Q_DECLARE_FLAGS(DockOptions, DockOption)
diff --git a/src/widgets/widgets/qmainwindowlayout.cpp b/src/widgets/widgets/qmainwindowlayout.cpp
index 3620aa04fc..ee76720a27 100644
--- a/src/widgets/widgets/qmainwindowlayout.cpp
+++ b/src/widgets/widgets/qmainwindowlayout.cpp
@@ -1,6 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2015 The Qt Company Ltd.
+** Copyright (C) 2015 Olivier Goffart <ogoffart@woboq.com>
 ** Contact: http://www.qt.io/licensing/
 **
 ** This file is part of the QtWidgets module of the Qt Toolkit.
@@ -49,6 +50,7 @@
 #include <qstatusbar.h>
 #include <qstring.h>
 #include <qstyle.h>
+#include <qstylepainter.h>
 #include <qvarlengtharray.h>
 #include <qstack.h>
 #include <qmap.h>
@@ -61,6 +63,7 @@
 
 #include <private/qapplication_p.h>
 #include <private/qlayoutengine_p.h>
+#include <private/qwidgetresizehandler_p.h>
 #ifdef Q_DEAD_CODE_FROM_QT4_MAC
 #   include <private/qcore_mac_p.h>
 #   include <private/qt_cocoa_helpers_mac_p.h>
@@ -68,9 +71,7 @@
 
 QT_BEGIN_NAMESPACE
 
-#ifdef QT_NO_DOCKWIDGET
 extern QMainWindowLayout *qt_mainwindow_layout(const QMainWindow *window);
-#endif
 
 /******************************************************************************
 ** debug
@@ -165,6 +166,242 @@ QDebug operator<<(QDebug debug, const QMainWindowLayout *layout)
 #endif // !defined(QT_NO_DOCKWIDGET) && !defined(QT_NO_DEBUG)
 
 /******************************************************************************
+ ** QDockWidgetGroupWindow
+ */
+// QDockWidgetGroupWindow is the floating window containing the tabbed dockwidgets in case several
+// dockwidgets are dragged together (QMainWindow::GroupedDragging feature).
+// QDockWidgetGroupLayout is the layout of that window and use a QDockAreaLayoutInfo to layout
+// the tabs inside it.
+#ifndef QT_NO_DOCKWIDGET
+class QDockWidgetGroupLayout : public QLayout {
+    QDockAreaLayoutInfo info;
+    QWidgetResizeHandler *resizer;
+public:
+    QDockWidgetGroupLayout(QWidget* parent) : QLayout(parent) {
+        setSizeConstraint(QLayout::SetMinAndMaxSize);
+        resizer = new QWidgetResizeHandler(parent);
+        resizer->setMovingEnabled(false);
+    }
+    ~QDockWidgetGroupLayout() {
+        info.deleteAllLayoutItems();
+    }
+
+    void addItem(QLayoutItem*) Q_DECL_OVERRIDE { Q_UNREACHABLE(); }
+    int count() const Q_DECL_OVERRIDE { return 0; }
+    QLayoutItem* itemAt(int index) const Q_DECL_OVERRIDE
+    {
+        int x = 0;
+        return info.itemAt(&x, index);
+    }
+    QLayoutItem* takeAt(int index) Q_DECL_OVERRIDE
+    {
+        int x = 0;
+        return info.takeAt(&x, index);
+    }
+    QSize sizeHint() const Q_DECL_OVERRIDE
+    {
+        int fw = frameWidth();
+        return info.sizeHint() + QSize(fw, fw);
+    }
+    QSize minimumSize() const Q_DECL_OVERRIDE
+    {
+        int fw = frameWidth();
+        return info.minimumSize() + QSize(fw, fw);
+    }
+    QSize maximumSize() const Q_DECL_OVERRIDE
+    {
+        int fw = frameWidth();
+        return info.maximumSize() + QSize(fw, fw);
+    }
+    void setGeometry(const QRect&r) Q_DECL_OVERRIDE
+    {
+        QDockAreaLayoutInfo *li = layoutInfo();
+        if (li->isEmpty()) {
+            static_cast<QDockWidgetGroupWindow *>(parent())->destroyIfEmpty();
+            return;
+        }
+        int fw = frameWidth();
+        li->reparentWidgets(parentWidget());
+        li->rect = r.adjusted(fw, fw, -fw, -fw);
+        li->fitItems();
+        li->apply(false);
+        resizer->setActive(QWidgetResizeHandler::Resize, !nativeWindowDeco());
+    }
+
+    QDockAreaLayoutInfo *layoutInfo() {
+        return &info;
+    }
+
+    bool nativeWindowDeco() const
+    {
+        return QDockWidgetLayout::wmSupportsNativeWindowDeco();
+    }
+
+    int frameWidth() const
+    {
+        return nativeWindowDeco() ? 0 :
+            parentWidget()->style()->pixelMetric(QStyle::PM_DockWidgetFrameWidth, 0, parentWidget());
+    }
+};
+
+// This item will be used in the layout for the gap item. We cannot use QWidgetItem directly
+// because QWidgetItem functions return an empty size for widgets are are floating.
+class QDockWidgetGroupWindowItem : public QWidgetItem
+{
+public:
+    QDockWidgetGroupWindowItem(QDockWidgetGroupWindow *parent) : QWidgetItem(parent) {}
+    QSize minimumSize() const Q_DECL_OVERRIDE { return lay()->minimumSize(); }
+    QSize maximumSize() const Q_DECL_OVERRIDE { return lay()->maximumSize(); }
+    QSize sizeHint() const Q_DECL_OVERRIDE { return lay()->sizeHint(); }
+
+private:
+    QLayout *lay() const { return const_cast<QDockWidgetGroupWindowItem *>(this)->widget()->layout(); }
+};
+
+bool QDockWidgetGroupWindow::event(QEvent *e)
+{
+    switch (e->type()) {
+    case QEvent::Close:
+        // Forward the close to the QDockWidget just as if its close button was pressed
+        if (QDockWidget *dw = topDockWidget()) {
+            e->ignore();
+            dw->close();
+            adjustFlags();
+        }
+        return true;
+    case QEvent::Move:
+        // Let QDockWidgetPrivate::moseEvent handle the dragging
+        if (QDockWidget *dw = topDockWidget())
+            static_cast<QDockWidgetPrivate *>(QObjectPrivate::get(dw))->moveEvent(static_cast<QMoveEvent*>(e));
+        return true;
+    case QEvent::NonClientAreaMouseMove:
+    case QEvent::NonClientAreaMouseButtonPress:
+    case QEvent::NonClientAreaMouseButtonRelease:
+    case QEvent::NonClientAreaMouseButtonDblClick:
+        // Let the QDockWidgetPrivate of the currently visible dock widget handle the drag and drop
+        if (QDockWidget *dw = topDockWidget())
+            static_cast<QDockWidgetPrivate *>(QObjectPrivate::get(dw))->nonClientAreaMouseEvent(static_cast<QMouseEvent*>(e));
+        return true;
+    case QEvent::ChildAdded:
+        if (qobject_cast<QDockWidget *>(static_cast<QChildEvent*>(e)->child()))
+            adjustFlags();
+        break;
+    default:
+        break;
+    }
+    return QWidget::event(e);
+}
+
+void QDockWidgetGroupWindow::paintEvent(QPaintEvent *)
+{
+    QDockWidgetGroupLayout *lay = static_cast<QDockWidgetGroupLayout *>(layout());
+    bool nativeDeco = lay->nativeWindowDeco();
+
+    if (!nativeDeco) {
+        QStyleOptionFrame framOpt;
+        framOpt.init(this);
+        QStylePainter p(this);
+        p.drawPrimitive(QStyle::PE_FrameDockWidget, framOpt);
+    }
+}
+
+QDockAreaLayoutInfo *QDockWidgetGroupWindow::layoutInfo() const
+{
+    return static_cast<QDockWidgetGroupLayout*>(layout())->layoutInfo();
+}
+
+/*! \internal
+    Returns the currently active QDockWidget.
+ */
+QDockWidget *QDockWidgetGroupWindow::topDockWidget() const
+{
+    QDockAreaLayoutInfo *info = layoutInfo();
+    QDockWidget *dw = 0;
+    if (info->tabBar && info->tabBar->currentIndex() >= 0) {
+        int i = info->tabIndexToListIndex(info->tabBar->currentIndex());
+        if (i >= 0) {
+            const QDockAreaLayoutItem &item = info->item_list.at(i);
+            if (item.widgetItem)
+                dw = qobject_cast<QDockWidget *>(item.widgetItem->widget());
+        }
+    }
+    if (!dw) {
+        for (int i = 0; !dw && i < info->item_list.count(); ++i) {
+            const QDockAreaLayoutItem &item = info->item_list.at(i);
+            if (item.skip())
+                continue;
+            if (!item.widgetItem)
+                continue;
+            dw = qobject_cast<QDockWidget *>(item.widgetItem->widget());
+        }
+    }
+    return dw;
+}
+
+/*! \internal
+    Destroy this window if there is no more QDockWidget in it.
+ */
+void QDockWidgetGroupWindow::destroyIfEmpty()
+{
+    if (layoutInfo()->isEmpty()) {
+        // Make sure to reparent the possibly floating or hidden QDockWidgets to the parent
+        foreach (QDockWidget *dw,
+                 findChildren<QDockWidget *>(QString(), Qt::FindDirectChildrenOnly)) {
+            bool wasFloating = dw->isFloating();
+            bool wasHidden = dw->isHidden();
+            dw->setParent(parentWidget());
+            if (wasFloating) {
+                dw->setFloating(true);
+            } else {
+                // maybe it was hidden, we still have to put it back in the main layout.
+                QMainWindowLayout *ml = qt_mainwindow_layout(static_cast<QMainWindow*>(parentWidget()));
+                Qt::DockWidgetArea area = ml->dockWidgetArea(this);
+                if (area == Qt::NoDockWidgetArea)
+                    area = Qt::LeftDockWidgetArea;
+                static_cast<QMainWindow*>(parentWidget())->addDockWidget(area, dw);
+            }
+            if (!wasHidden)
+                dw->show();
+        }
+        foreach (QTabBar *tb, findChildren<QTabBar *>(QString(), Qt::FindDirectChildrenOnly))
+            tb->setParent(parentWidget());
+        deleteLater();
+    }
+}
+
+/*! \internal
+    Sets the flags of this window in accordence to the capabilities of the dock widgets
+ */
+void QDockWidgetGroupWindow::adjustFlags()
+{
+    QDockWidget *top = topDockWidget();
+    if (!top)
+        return;
+    const bool nativeDeco = static_cast<QDockWidgetGroupLayout *>(layout())->nativeWindowDeco();
+
+    Qt::WindowFlags oldFlags = windowFlags();
+    Qt::WindowFlags flags = oldFlags;
+    if (nativeDeco) {
+        flags |= Qt::CustomizeWindowHint | Qt::WindowTitleHint;
+        if (top->features() & QDockWidget::DockWidgetClosable)
+            flags |= Qt::WindowCloseButtonHint;
+        else
+            flags &= ~Qt::WindowCloseButtonHint;
+        flags &= ~Qt::FramelessWindowHint;
+    } else {
+        flags |= Qt::FramelessWindowHint;
+    }
+    if (oldFlags != flags) {
+        setWindowFlags(flags);
+        show(); // setWindowFlags hides the window
+    }
+
+    setWindowTitle(top->windowTitle());
+    setWindowIcon(top->windowIcon());
+}
+#endif
+
+/******************************************************************************
 ** QMainWindowLayoutState
 */
 
@@ -335,8 +572,8 @@ QList<int> QMainWindowLayoutState::indexOf(QWidget *widget) const
 
 #ifndef QT_NO_DOCKWIDGET
     // is it a dock widget?
-    if (QDockWidget *dockWidget = qobject_cast<QDockWidget *>(widget)) {
-        result = dockAreaLayout.indexOf(dockWidget);
+    if (qobject_cast<QDockWidget *>(widget) || qobject_cast<QDockWidgetGroupWindow *>(widget)) {
+        result = dockAreaLayout.indexOf(widget);
         if (!result.isEmpty())
             result.prepend(1);
         return result;
@@ -413,7 +650,8 @@ QList<int> QMainWindowLayoutState::gapIndex(QWidget *widget,
 
 #ifndef QT_NO_DOCKWIDGET
     // is it a dock widget?
-    if (qobject_cast<QDockWidget *>(widget) != 0) {
+    if (qobject_cast<QDockWidget *>(widget) != 0
+            || qobject_cast<QDockWidgetGroupWindow *>(widget)) {
         result = dockAreaLayout.gapIndex(pos);
         if (!result.isEmpty())
             result.prepend(1);
@@ -440,7 +678,7 @@ bool QMainWindowLayoutState::insertGap(const QList<int> &path, QLayoutItem *item
 
 #ifndef QT_NO_DOCKWIDGET
     if (i == 1) {
-        Q_ASSERT(qobject_cast<QDockWidget*>(item->widget()) != 0);
+        Q_ASSERT(qobject_cast<QDockWidget*>(item->widget()) || qobject_cast<QDockWidgetGroupWindow*>(item->widget()));
         return dockAreaLayout.insertGap(path.mid(1), item);
     }
 #endif //QT_NO_DOCKWIDGET
@@ -593,6 +831,17 @@ void QMainWindowLayoutState::saveState(QDataStream &stream) const
 {
 #ifndef QT_NO_DOCKWIDGET
     dockAreaLayout.saveState(stream);
+#ifndef QT_NO_TABBAR
+    QList<QDockWidgetGroupWindow *> floatingTabs =
+        mainWindow->findChildren<QDockWidgetGroupWindow *>(QString(), Qt::FindDirectChildrenOnly);
+
+    foreach (QDockWidgetGroupWindow *floating, floatingTabs) {
+        if (floating->layoutInfo()->isEmpty())
+            continue;
+        stream << uchar(QDockAreaLayout::FloatingDockWidgetTabMarker) << floating->geometry();
+        floating->layoutInfo()->saveState(stream);
+    }
+#endif
 #endif
 #ifndef QT_NO_TOOLBAR
     toolBarAreaLayout.saveState(stream);
@@ -638,12 +887,28 @@ bool QMainWindowLayoutState::checkFormat(QDataStream &stream)
             case QDockAreaLayout::DockWidgetStateMarker:
                 {
                     QList<QDockWidget *> dockWidgets = findChildrenHelper<QDockWidget*>(mainWindow);
+                    foreach (QDockWidgetGroupWindow *floating, findChildrenHelper<QDockWidgetGroupWindow*>(mainWindow))
+                        dockWidgets += findChildrenHelper<QDockWidget*>(floating);
                     if (!dockAreaLayout.restoreState(stream, dockWidgets, true /*testing*/)) {
                         return false;
                     }
                 }
                 break;
-#endif
+#ifndef QT_NO_TABBAR
+            case QDockAreaLayout::FloatingDockWidgetTabMarker:
+                {
+                    QRect geom;
+                    stream >> geom;
+                    QDockAreaLayoutInfo info;
+                    QList<QDockWidget *> dockWidgets = findChildrenHelper<QDockWidget*>(mainWindow);
+                    foreach (QDockWidgetGroupWindow *floating, findChildrenHelper<QDockWidgetGroupWindow*>(mainWindow))
+                        dockWidgets += findChildrenHelper<QDockWidget*>(floating);
+                    if (!info.restoreState(stream, dockWidgets, true /* testing*/))
+                        return false;
+                }
+                break;
+#endif // QT_NO_TABBAR
+#endif // QT_NO_DOCKWIDGET
             default:
                 //there was an error during the parsing
                 return false;
@@ -682,6 +947,8 @@ bool QMainWindowLayoutState::restoreState(QDataStream &_stream,
             case QDockAreaLayout::DockWidgetStateMarker:
                 {
                     QList<QDockWidget *> dockWidgets = findChildrenHelper<QDockWidget*>(mainWindow);
+                    foreach (QDockWidgetGroupWindow *floating, findChildrenHelper<QDockWidgetGroupWindow*>(mainWindow))
+                        dockWidgets += findChildrenHelper<QDockWidget*>(floating);
                     if (!dockAreaLayout.restoreState(stream, dockWidgets))
                         return false;
 
@@ -702,6 +969,26 @@ bool QMainWindowLayoutState::restoreState(QDataStream &_stream,
                     }
                 }
                 break;
+#ifndef QT_NO_TABBAR
+            case QDockAreaLayout::FloatingDockWidgetTabMarker:
+            {
+                QList<QDockWidget *> dockWidgets = findChildrenHelper<QDockWidget*>(mainWindow);
+                foreach (QDockWidgetGroupWindow *floating, findChildrenHelper<QDockWidgetGroupWindow*>(mainWindow))
+                    dockWidgets += findChildrenHelper<QDockWidget*>(floating);
+                QDockWidgetGroupWindow* floatingTab = qt_mainwindow_layout(mainWindow)->createTabbedDockWindow();
+                *floatingTab->layoutInfo() = QDockAreaLayoutInfo(&dockAreaLayout.sep, QInternal::LeftDock,
+                                                                 Qt::Horizontal, QTabBar::RoundedSouth, mainWindow);
+                QRect geometry;
+                stream >> geometry;
+                if (!floatingTab->layoutInfo()->restoreState(stream, dockWidgets, false))
+                    return false;
+                geometry = QDockAreaLayout::constrainedRect(geometry, floatingTab);
+                floatingTab->move(geometry.topLeft());
+                floatingTab->resize(geometry.size());
+                floatingTab->show();
+            }
+            break;
+#endif // QT_NO_TABBAR
 #endif // QT_NO_DOCKWIDGET
 
 #ifndef QT_NO_TOOLBAR
@@ -1223,7 +1510,7 @@ void QMainWindowLayout::splitDockWidget(QDockWidget *after,
     invalidate();
 }
 
-Qt::DockWidgetArea QMainWindowLayout::dockWidgetArea(QDockWidget *widget) const
+Qt::DockWidgetArea QMainWindowLayout::dockWidgetArea(QWidget *widget) const
 {
     QList<int> pathToWidget = layoutState.dockAreaLayout.indexOf(widget);
     if (pathToWidget.isEmpty())
@@ -1238,20 +1525,88 @@ void QMainWindowLayout::keepSize(QDockWidget *w)
 
 #ifndef QT_NO_TABBAR
 
+// Handle custom tooltip, and allow to drag tabs away.
 class QMainWindowTabBar : public QTabBar
 {
+    QMainWindow *mainWindow;
+    QDockWidget *draggingDock; // Currently dragging (detached) dock widget
 public:
-    QMainWindowTabBar(QWidget *parent);
+    QMainWindowTabBar(QMainWindow *parent);
 protected:
     bool event(QEvent *e) Q_DECL_OVERRIDE;
+    void mouseReleaseEvent(QMouseEvent*) Q_DECL_OVERRIDE;
+    void mouseMoveEvent(QMouseEvent*) Q_DECL_OVERRIDE;
+
 };
 
-QMainWindowTabBar::QMainWindowTabBar(QWidget *parent)
-    : QTabBar(parent)
+QMainWindowTabBar::QMainWindowTabBar(QMainWindow *parent)
+    : QTabBar(parent), mainWindow(parent), draggingDock(0)
 {
     setExpanding(false);
 }
 
+void QMainWindowTabBar::mouseMoveEvent(QMouseEvent *e)
+{
+    // The QTabBar handles the moving (reordering) of tabs.
+    // When QTabBarPrivate::dragInProgress is true, and that the mouse is outside of a region
+    // around the QTabBar, we will consider the user wants to drag that QDockWidget away from this
+    // tab area.
+
+    QTabBarPrivate *d = static_cast<QTabBarPrivate*>(d_ptr.data());
+    if (!draggingDock && (mainWindow->dockOptions() & QMainWindow::GroupedDragging)) {
+        int offset = QApplication::startDragDistance() + 1;
+        offset *= 3;
+        QRect r = rect().adjusted(-offset, -offset, offset, offset);
+        if (d->dragInProgress && !r.contains(e->pos()) && d->validIndex(d->pressedIndex)) {
+            QMainWindowLayout* mlayout = qt_mainwindow_layout(mainWindow);
+            QDockAreaLayoutInfo *info = mlayout->dockInfo(this);
+            Q_ASSERT(info);
+            int idx = info->tabIndexToListIndex(d->pressedIndex);
+            const QDockAreaLayoutItem &item = info->item_list.at(idx);
+            if (item.widgetItem
+                    && (draggingDock = qobject_cast<QDockWidget *>(item.widgetItem->widget()))) {
+                // We should drag this QDockWidget away by unpluging it.
+                // First cancel the QTabBar's internal move
+                d->moveTabFinished(d->pressedIndex);
+                d->pressedIndex = -1;
+                if (d->movingTab)
+                    d->movingTab->setVisible(false);
+                d->dragStartPosition = QPoint();
+
+                // Then starts the drag using QDockWidgetPrivate's API
+                QDockWidgetPrivate *dockPriv = static_cast<QDockWidgetPrivate *>(QObjectPrivate::get(draggingDock));
+                QDockWidgetLayout *dwlayout = static_cast<QDockWidgetLayout *>(draggingDock->layout());
+                dockPriv->initDrag(dwlayout->titleArea().center(), true);
+                dockPriv->startDrag(false);
+                if (dockPriv->state)
+                    dockPriv->state->ctrlDrag = e->modifiers() & Qt::ControlModifier;
+            }
+        }
+    }
+
+    if (draggingDock) {
+        QDockWidgetPrivate *dockPriv = static_cast<QDockWidgetPrivate *>(QObjectPrivate::get(draggingDock));
+        if (dockPriv->state && dockPriv->state->dragging) {
+            QPoint pos = e->globalPos() - dockPriv->state->pressPos;
+            draggingDock->move(pos);
+            // move will call QMainWindowLayout::hover
+        }
+    }
+    QTabBar::mouseMoveEvent(e);
+}
+
+void QMainWindowTabBar::mouseReleaseEvent(QMouseEvent *e)
+{
+    if (draggingDock && e->button() == Qt::LeftButton) {
+        QDockWidgetPrivate *dockPriv = static_cast<QDockWidgetPrivate *>(QObjectPrivate::get(draggingDock));
+        if (dockPriv->state && dockPriv->state->dragging) {
+            dockPriv->endDrag();
+        }
+        draggingDock = 0;
+    }
+    QTabBar::mouseReleaseEvent(e);
+}
+
 bool QMainWindowTabBar::event(QEvent *e)
 {
     // show the tooltip if tab is too small to fit label
@@ -1276,7 +1631,7 @@ QTabBar *QMainWindowLayout::getTabBar()
     if (!unusedTabBars.isEmpty()) {
         result = unusedTabBars.takeLast();
     } else {
-        result = new QMainWindowTabBar(parentWidget());
+        result = new QMainWindowTabBar(static_cast<QMainWindow *>(parentWidget()));
         result->setDrawBase(true);
         result->setElideMode(Qt::ElideRight);
         result->setDocumentMode(_documentMode);
@@ -1305,12 +1660,30 @@ QWidget *QMainWindowLayout::getSeparatorWidget()
     return result;
 }
 
+/*! \internal
+    Returns a pointer QDockAreaLayoutInfo which contains this \a widget directly
+    (in its internal list)
+ */
+QDockAreaLayoutInfo *QMainWindowLayout::dockInfo(QWidget *widget)
+{
+    QDockAreaLayoutInfo *info = layoutState.dockAreaLayout.info(widget);
+    if (info)
+        return info;
+    foreach (QDockWidgetGroupWindow *dwgw,
+             parent()->findChildren<QDockWidgetGroupWindow*>(QString(), Qt::FindDirectChildrenOnly)) {
+        info = dwgw->layoutInfo()->info(widget);
+        if (info)
+            return info;
+    }
+    return 0;
+}
+
 void QMainWindowLayout::tabChanged()
 {
     QTabBar *tb = qobject_cast<QTabBar*>(sender());
     if (tb == 0)
         return;
-    QDockAreaLayoutInfo *info = layoutState.dockAreaLayout.info(tb);
+    QDockAreaLayoutInfo *info = dockInfo(tb);
     if (info == 0)
         return;
     info->apply(false);
@@ -1323,7 +1696,7 @@ void QMainWindowLayout::tabMoved(int from, int to)
 {
     QTabBar *tb = qobject_cast<QTabBar*>(sender());
     Q_ASSERT(tb);
-    QDockAreaLayoutInfo *info = layoutState.dockAreaLayout.info(tb);
+    QDockAreaLayoutInfo *info = dockInfo(tb);
     Q_ASSERT(info);
 
     info->moveTab(from, to);
@@ -1365,7 +1738,7 @@ bool QMainWindowLayout::endSeparatorMove(const QPoint&)
 
 void QMainWindowLayout::raise(QDockWidget *widget)
 {
-    QDockAreaLayoutInfo *info = layoutState.dockAreaLayout.info(widget);
+    QDockAreaLayoutInfo *info = dockInfo(widget);
     if (info == 0)
         return;
 #ifndef QT_NO_TABBAR
@@ -1549,6 +1922,8 @@ void QMainWindowLayout::revert(QLayoutItem *widgetItem)
     QWidget *widget = widgetItem->widget();
     layoutState = savedState;
     currentGapPos = layoutState.indexOf(widget);
+    if (currentGapPos.isEmpty())
+        return;
     fixToolBarOrientation(widgetItem, currentGapPos.at(1));
     layoutState.unplug(currentGapPos);
     layoutState.fitLayout();
@@ -1613,6 +1988,42 @@ void QMainWindowLayout::animationFinished(QWidget *widget)
     if (widget == pluggingWidget) {
 
 #ifndef QT_NO_DOCKWIDGET
+        if (QDockWidgetGroupWindow *dwgw = qobject_cast<QDockWidgetGroupWindow *>(widget)) {
+            // When the animated widget was a QDockWidgetGroupWindow, it means each of the
+            // embedded QDockWidget needs to be plugged back into the QMainWindow layout.
+            savedState.clear();
+            QDockAreaLayoutInfo* info = dwgw->layoutInfo();
+            QList<int> path = layoutState.dockAreaLayout.indexOf(widget);
+            Q_ASSERT(path.size() >= 2);
+
+            QDockAreaLayoutInfo* parentInfo = layoutState.dockAreaLayout.info(path);
+            Q_ASSERT(parentInfo);
+            if (parentInfo->tabbed) {
+                // merge the two tab widgets
+                int idx = path.last();
+                Q_ASSERT(parentInfo->item_list[idx].widgetItem->widget() == dwgw);
+                delete parentInfo->item_list[idx].widgetItem;
+                parentInfo->item_list.removeAt(idx);
+                std::copy(info->item_list.cbegin(), info->item_list.cend(),
+                          std::inserter(parentInfo->item_list, parentInfo->item_list.begin() + idx));
+                quintptr currentId = info->currentTabId();
+                *info = QDockAreaLayoutInfo();
+                parentInfo->reparentWidgets(parentWidget());
+                parentInfo->updateTabBar();
+                parentInfo->setCurrentTabId(currentId);
+            } else {
+                QDockAreaLayoutItem &item = layoutState.dockAreaLayout.item(path);
+                Q_ASSERT(item.widgetItem->widget() == dwgw);
+                delete item.widgetItem;
+                item.widgetItem = 0;
+                item.subinfo = new QDockAreaLayoutInfo(qMove(*info));
+                *info = QDockAreaLayoutInfo();
+                item.subinfo->reparentWidgets(parentWidget());
+                item.subinfo->setTabBarShape(parentInfo->tabBarShape);
+            }
+            dwgw->destroyIfEmpty();
+        }
+
         if (QDockWidget *dw = qobject_cast<QDockWidget*>(widget))
             dw->d_func()->plug(currentGapRect);
 #endif
@@ -1633,7 +2044,7 @@ void QMainWindowLayout::animationFinished(QWidget *widget)
         if (qobject_cast<QDockWidget*>(widget) != 0) {
             // info() might return null if the widget is destroyed while
             // animating but before the animationFinished signal is received.
-            if (QDockAreaLayoutInfo *info = layoutState.dockAreaLayout.info(widget))
+            if (QDockAreaLayoutInfo *info = dockInfo(widget))
                 info->setCurrentTab(widget);
         }
 #endif
@@ -1777,8 +2188,33 @@ void QMainWindowLayout::setCentralWidget(QWidget *widget)
     invalidate();
 }
 
-QLayoutItem *QMainWindowLayout::unplug(QWidget *widget)
-{
+/*! \internal
+    Unplug \a widget (QDockWidget or QToolBar) from it's parent container.
+
+    If \a group is true we might actually unplug the group of tabs this
+    widget is part if QMainWindow::GroupedDragging is set. When \a group
+    is false, the widget itself is always unplugged alone
+
+    Returns the QLayoutItem of the dragged element.
+    The layout item is kept in the layout but set as a gap item.
+ */
+QLayoutItem *QMainWindowLayout::unplug(QWidget *widget, bool group)
+{
+#if !defined(QT_NO_DOCKWIDGET) && !defined(QT_NO_TABBAR)
+    QDockWidgetGroupWindow *floatingParent = qobject_cast<QDockWidgetGroupWindow *>(widget->parentWidget());
+    if (group && floatingParent && !widget->isWindow()) {
+        // We are just dragging a floating window as it, not need to do anything, we just have to
+        // look up the corresponding QWidgetItem* if it exists
+        QList<int> tabbedWindowPath = layoutState.indexOf(widget->parentWidget());
+        return tabbedWindowPath.isEmpty() ? 0 : layoutState.item(tabbedWindowPath);
+    } else if (floatingParent) {
+        // We are unplugging a dock widget from a floating window.
+        if (QDockWidget *dw = qobject_cast<QDockWidget*>(widget)) {
+            dw->d_func()->unplug(widget->geometry());
+            return 0;
+        }
+    }
+#endif
     QList<int> path = layoutState.indexOf(widget);
     if (path.isEmpty())
         return 0;
@@ -1792,9 +2228,35 @@ QLayoutItem *QMainWindowLayout::unplug(QWidget *widget)
 
 #ifndef QT_NO_DOCKWIDGET
     if (QDockWidget *dw = qobject_cast<QDockWidget*>(widget)) {
-        dw->d_func()->unplug(r);
+        Q_ASSERT(path.first() == 1);
+        bool actualGroup = false;
+#ifndef QT_NO_TABBAR
+        if (group && (dockOptions & QMainWindow::GroupedDragging) && path.size() > 3) {
+            QDockAreaLayoutItem &parentItem = layoutState.dockAreaLayout.item(path.mid(1, path.size() - 2));
+            if (parentItem.subinfo && parentItem.subinfo->tabbed) {
+                // The QDockWidget is part of a group of tab and we need to unplug them all.
+                actualGroup = true;
+                path.removeLast();
+
+                QDockWidgetGroupWindow* floatingTabs = createTabbedDockWindow();
+                QDockAreaLayoutInfo* info = floatingTabs->layoutInfo();
+                *info = qMove(*parentItem.subinfo);
+                delete parentItem.subinfo;
+                parentItem.subinfo = 0;
+                floatingTabs->setGeometry(info->rect.translated(parentWidget()->pos()));
+                floatingTabs->show();
+                floatingTabs->raise();
+                item = new QDockWidgetGroupWindowItem(floatingTabs);
+                parentItem.widgetItem = item;
+                savedState = layoutState;
+            }
+        }
+#endif // QT_NO_TABBAR
+        if (!actualGroup) {
+            dw->d_func()->unplug(r);
+        }
     }
-#endif
+#endif // QT_NO_DOCKWIDGET
 #ifndef QT_NO_TOOLBAR
     if (QToolBar *tb = qobject_cast<QToolBar*>(widget)) {
         tb->d_func()->unplug(r);
@@ -1841,6 +2303,9 @@ QList<int> QMainWindowLayout::hover(QLayoutItem *widgetItem, const QPoint &mouse
 #ifndef QT_NO_DOCKWIDGET
         if (QDockWidget *dw = qobject_cast<QDockWidget*>(widget))
             allowed = dw->isAreaAllowed(toDockWidgetArea(path.at(1)));
+
+        if (qobject_cast<QDockWidgetGroupWindow *>(widget))
+            allowed = true;
 #endif
 #ifndef QT_NO_TOOLBAR
         if (QToolBar *tb = qobject_cast<QToolBar*>(widget))
@@ -1893,11 +2358,23 @@ QList<int> QMainWindowLayout::hover(QLayoutItem *widgetItem, const QPoint &mouse
     return path;
 }
 
+QDockWidgetGroupWindow *QMainWindowLayout::createTabbedDockWindow()
+{
+    QDockWidgetGroupWindow* f = new QDockWidgetGroupWindow(parentWidget(), Qt::Tool);
+    new QDockWidgetGroupLayout(f);
+    return f;
+}
+
 void QMainWindowLayout::applyState(QMainWindowLayoutState &newState, bool animate)
 {
 #ifndef QT_NO_DOCKWIDGET
 #ifndef QT_NO_TABBAR
     QSet<QTabBar*> used = newState.dockAreaLayout.usedTabBars();
+    foreach (QDockWidgetGroupWindow *dwgw,
+             parent()->findChildren<QDockWidgetGroupWindow*>(QString(), Qt::FindDirectChildrenOnly)) {
+        used += dwgw->layoutInfo()->usedTabBars();
+    }
+
     QSet<QTabBar*> retired = usedTabBars - used;
     usedTabBars = used;
     foreach (QTabBar *tab_bar, retired) {
@@ -1916,6 +2393,8 @@ void QMainWindowLayout::applyState(QMainWindowLayoutState &newState, bool animat
         }
     }
 
+    for (int i = 0; i < QInternal::DockCount; ++i)
+        newState.dockAreaLayout.docks[i].reparentWidgets(parentWidget());
 
 #endif // QT_NO_TABBAR
 #endif // QT_NO_DOCKWIDGET
diff --git a/src/widgets/widgets/qmainwindowlayout_p.h b/src/widgets/widgets/qmainwindowlayout_p.h
index 8ccb4d303f..9155c5fb23 100644
--- a/src/widgets/widgets/qmainwindowlayout_p.h
+++ b/src/widgets/widgets/qmainwindowlayout_p.h
@@ -77,6 +77,23 @@ QT_BEGIN_NAMESPACE
 class QToolBar;
 class QRubberBand;
 
+#ifndef QT_NO_DOCKWIDGET
+class QDockWidgetGroupWindow : public QWidget
+{
+    Q_OBJECT
+public:
+    explicit QDockWidgetGroupWindow(QWidget* parent = 0, Qt::WindowFlags f = 0)
+        : QWidget(parent, f) {}
+    QDockAreaLayoutInfo *layoutInfo() const;
+    QDockWidget *topDockWidget() const;
+    void destroyIfEmpty();
+    void adjustFlags();
+protected:
+    bool event(QEvent *) Q_DECL_OVERRIDE;
+    void paintEvent(QPaintEvent*) Q_DECL_OVERRIDE;
+};
+#endif
+
 /* This data structure represents the state of all the tool-bars and dock-widgets. It's value based
    so it can be easilly copied into a temporary variable. All operations are performed without moving
    any widgets. Only when we are sure we have the desired state, we call apply(), which moves the
@@ -196,10 +213,11 @@ public:
                          QDockWidget *dockwidget,
                          Qt::Orientation orientation);
     void tabifyDockWidget(QDockWidget *first, QDockWidget *second);
-    Qt::DockWidgetArea dockWidgetArea(QDockWidget *dockwidget) const;
+    Qt::DockWidgetArea dockWidgetArea(QWidget* widget) const;
     void raise(QDockWidget *widget);
     void setVerticalTabsEnabled(bool enabled);
     bool restoreDockWidget(QDockWidget *dockwidget);
+    QDockAreaLayoutInfo *dockInfo(QWidget *w);
 
 #ifndef QT_NO_TABBAR
     bool _documentMode;
@@ -224,6 +242,8 @@ public:
     void setTabShape(QTabWidget::TabShape tabShape);
     QTabWidget::TabPosition tabPosition(Qt::DockWidgetArea area) const;
     void setTabPosition(Qt::DockWidgetAreas areas, QTabWidget::TabPosition tabPosition);
+
+    QDockWidgetGroupWindow *createTabbedDockWindow();
 #endif // QT_NO_TABWIDGET
 #endif // QT_NO_TABBAR
 
@@ -273,7 +293,7 @@ public:
 
     QList<int> hover(QLayoutItem *widgetItem, const QPoint &mousePos);
     bool plug(QLayoutItem *widgetItem);
-    QLayoutItem *unplug(QWidget *widget);
+    QLayoutItem *unplug(QWidget *widget, bool group = false);
     void revert(QLayoutItem *widgetItem);
     void updateGapIndicator();
     void paintDropIndicator(QPainter *p, QWidget *widget, const QRegion &clip);
diff --git a/src/widgets/widgets/qmenu.cpp b/src/widgets/widgets/qmenu.cpp
index 1749f9d8c7..4403deda8e 100644
--- a/src/widgets/widgets/qmenu.cpp
+++ b/src/widgets/widgets/qmenu.cpp
@@ -183,7 +183,7 @@ void QMenuPrivate::setPlatformMenu(QPlatformMenu *menu)
 }
 
 // forward declare function
-static void copyActionToPlatformItem(const QAction *action, QPlatformMenuItem* item);
+static void copyActionToPlatformItem(const QAction *action, QPlatformMenuItem *item, QPlatformMenu *itemsMenu);
 
 void QMenuPrivate::syncPlatformMenu()
 {
@@ -200,7 +200,7 @@ void QMenuPrivate::syncPlatformMenu()
         menuItem->setTag(reinterpret_cast<quintptr>(action));
         QObject::connect(menuItem, SIGNAL(activated()), action, SLOT(trigger()), Qt::QueuedConnection);
         QObject::connect(menuItem, SIGNAL(hovered()), action, SIGNAL(hovered()), Qt::QueuedConnection);
-        copyActionToPlatformItem(action, menuItem);
+        copyActionToPlatformItem(action, menuItem, platformMenu.data());
         platformMenu->insertMenuItem(menuItem, beforeItem);
         beforeItem = menuItem;
     }
@@ -1110,8 +1110,7 @@ bool QMenuPrivate::mouseEventTaken(QMouseEvent *e)
             handleEnterLeaveEvents(&previousMouseMenu,qobject_cast<QMenu *>(caused));
             if(e->type() != QEvent::MouseButtonRelease || mouseDown == caused) {
             QMouseEvent new_e(e->type(), cpos, caused->mapTo(caused->topLevelWidget(), cpos), e->screenPos(),
-                              e->button(), e->buttons(), e->modifiers());
-            QGuiApplicationPrivate::setMouseEventSource(&new_e, e->source());
+                              e->button(), e->buttons(), e->modifiers(), e->source());
             QApplication::sendEvent(caused, &new_e);
             return true;
             }
@@ -3105,7 +3104,7 @@ QMenu::timerEvent(QTimerEvent *e)
     }
 }
 
-static void copyActionToPlatformItem(const QAction *action, QPlatformMenuItem* item)
+static void copyActionToPlatformItem(const QAction *action, QPlatformMenuItem *item, QPlatformMenu *itemsMenu)
 {
     item->setText(action->text());
     item->setIsSeparator(action->isSeparator());
@@ -3131,6 +3130,8 @@ static void copyActionToPlatformItem(const QAction *action, QPlatformMenuItem* i
     item->setEnabled(action->isEnabled());
 
     if (action->menu()) {
+        if (!action->menu()->platformMenu())
+            action->menu()->setPlatformMenu(itemsMenu->createSubMenu());
         item->setMenu(action->menu()->platformMenu());
     } else {
         item->setMenu(0);
@@ -3185,7 +3186,7 @@ void QMenu::actionEvent(QActionEvent *e)
             menuItem->setTag(reinterpret_cast<quintptr>(e->action()));
             QObject::connect(menuItem, SIGNAL(activated()), e->action(), SLOT(trigger()));
             QObject::connect(menuItem, SIGNAL(hovered()), e->action(), SIGNAL(hovered()));
-            copyActionToPlatformItem(e->action(), menuItem);
+            copyActionToPlatformItem(e->action(), menuItem, d->platformMenu);
             QPlatformMenuItem* beforeItem = d->platformMenu->menuItemForTag(reinterpret_cast<quintptr>(e->before()));
             d->platformMenu->insertMenuItem(menuItem, beforeItem);
         } else if (e->type() == QEvent::ActionRemoved) {
@@ -3195,7 +3196,7 @@ void QMenu::actionEvent(QActionEvent *e)
         } else if (e->type() == QEvent::ActionChanged) {
             QPlatformMenuItem *menuItem = d->platformMenu->menuItemForTag(reinterpret_cast<quintptr>(e->action()));
             if (menuItem) {
-                copyActionToPlatformItem(e->action(), menuItem);
+                copyActionToPlatformItem(e->action(), menuItem, d->platformMenu);
                 d->platformMenu->syncMenuItem(menuItem);
             }
         }
diff --git a/src/widgets/widgets/qmenubar.cpp b/src/widgets/widgets/qmenubar.cpp
index 4659d9cf6c..1ad99bed9c 100644
--- a/src/widgets/widgets/qmenubar.cpp
+++ b/src/widgets/widgets/qmenubar.cpp
@@ -1632,7 +1632,7 @@ QSize QMenuBar::sizeHint() const
     if(d->leftWidget) {
         QSize sz = d->leftWidget->sizeHint();
         sz.rheight() += margin;
-        ret.expandedTo(sz);
+        ret = ret.expandedTo(sz);
     }
     if(d->rightWidget) {
         QSize sz = d->rightWidget->sizeHint();
diff --git a/src/widgets/widgets/qsplitter.cpp b/src/widgets/widgets/qsplitter.cpp
index de6e45234c..38773a4fbf 100644
--- a/src/widgets/widgets/qsplitter.cpp
+++ b/src/widgets/widgets/qsplitter.cpp
@@ -58,6 +58,10 @@ QT_BEGIN_NAMESPACE
 
 //#define QSPLITTER_DEBUG
 
+QSplitterPrivate::~QSplitterPrivate()
+{
+}
+
 /*!
     \class QSplitterHandle
     \brief The QSplitterHandle class provides handle functionality for the splitter.
diff --git a/src/widgets/widgets/qsplitter_p.h b/src/widgets/widgets/qsplitter_p.h
index a45f776da1..890bd535ec 100644
--- a/src/widgets/widgets/qsplitter_p.h
+++ b/src/widgets/widgets/qsplitter_p.h
@@ -76,6 +76,7 @@ class QSplitterPrivate : public QFramePrivate
 public:
     QSplitterPrivate() : rubberBand(0), opaque(true), firstShow(true),
                          childrenCollapsible(true), compatMode(false), handleWidth(-1), blockChildAdd(false), opaqueResizeSet(false) {}
+    ~QSplitterPrivate();
 
     QPointer<QRubberBand> rubberBand;
     mutable QList<QSplitterLayoutStruct *> list;
diff --git a/src/widgets/widgets/qstackedwidget.cpp b/src/widgets/widgets/qstackedwidget.cpp
index 2cec8a0b9c..19a2edf0f2 100644
--- a/src/widgets/widgets/qstackedwidget.cpp
+++ b/src/widgets/widgets/qstackedwidget.cpp
@@ -182,7 +182,9 @@ int QStackedWidget::insertWidget(int index, QWidget *widget)
     not deleted but simply removed from the stacked layout, causing it
     to be hidden.
 
-    \b{Note:} Ownership of \a widget reverts to the application.
+    \note Parent object and parent widget of \a widget will remain the
+    QStackedWidget. If the application wants to reuse the removed
+    \a widget, then it is recommended to re-parent it.
 
     \sa addWidget(), insertWidget(), currentWidget()
 */
diff --git a/src/widgets/widgets/qtoolbutton.cpp b/src/widgets/widgets/qtoolbutton.cpp
index 5a56c592a6..8473b261fc 100644
--- a/src/widgets/widgets/qtoolbutton.cpp
+++ b/src/widgets/widgets/qtoolbutton.cpp
@@ -897,7 +897,7 @@ void QToolButton::setDefaultAction(QAction *action)
         return;
     if (!actions().contains(action))
         addAction(action);
-    setText(action->iconText());
+    setText(action->text());
     setIcon(action->icon());
 #ifndef QT_NO_TOOLTIP
     setToolTip(action->toolTip());
diff --git a/src/widgets/widgets/qwidgetlinecontrol.cpp b/src/widgets/widgets/qwidgetlinecontrol.cpp
index 759e41a5fa..436937be72 100644
--- a/src/widgets/widgets/qwidgetlinecontrol.cpp
+++ b/src/widgets/widgets/qwidgetlinecontrol.cpp
@@ -189,7 +189,7 @@ void QWidgetLineControl::commitPreedit()
 
     m_preeditCursor = 0;
     setPreeditArea(-1, QString());
-    m_textLayout.clearAdditionalFormats();
+    m_textLayout.clearFormats();
     updateDisplayText(/*force*/ true);
 #endif
 }
@@ -557,7 +557,8 @@ void QWidgetLineControl::processInputMethodEvent(QInputMethodEvent *event)
     const int oldPreeditCursor = m_preeditCursor;
     m_preeditCursor = event->preeditString().length();
     m_hideCursor = false;
-    QList<QTextLayout::FormatRange> formats;
+    QVector<QTextLayout::FormatRange> formats;
+    formats.reserve(event->attributes().size());
     for (int i = 0; i < event->attributes().size(); ++i) {
         const QInputMethodEvent::Attribute &a = event->attributes().at(i);
         if (a.type == QInputMethodEvent::Cursor) {
@@ -574,7 +575,7 @@ void QWidgetLineControl::processInputMethodEvent(QInputMethodEvent *event)
             }
         }
     }
-    m_textLayout.setAdditionalFormats(formats);
+    m_textLayout.setFormats(formats);
     updateDisplayText(/*force*/ true);
     if (cursorPositionChanged)
         emitCursorPositionChanged();
diff --git a/src/widgets/widgets/qwidgettextcontrol.cpp b/src/widgets/widgets/qwidgettextcontrol.cpp
index faa63cb400..22d199fc74 100644
--- a/src/widgets/widgets/qwidgettextcontrol.cpp
+++ b/src/widgets/widgets/qwidgettextcontrol.cpp
@@ -883,7 +883,8 @@ void QWidgetTextControl::setTextCursor(const QTextCursor &cursor)
     const bool posChanged = cursor.position() != d->cursor.position();
     const QTextCursor oldSelection = d->cursor;
     d->cursor = cursor;
-    d->cursorOn = d->hasFocus && (d->interactionFlags & Qt::TextEditable);
+    d->cursorOn = d->hasFocus
+            && (d->interactionFlags & (Qt::TextSelectableByKeyboard | Qt::TextEditable));
     d->_q_updateCurrentCharFormatAndSelection();
     ensureCursorVisible();
     d->repaintOldAndNewSelection(oldSelection);
@@ -2028,7 +2029,8 @@ void QWidgetTextControlPrivate::inputMethodEvent(QInputMethodEvent *e)
     QTextLayout *layout = block.layout();
     if (isGettingInput)
         layout->setPreeditArea(cursor.position() - block.position(), e->preeditString());
-    QList<QTextLayout::FormatRange> overrides;
+    QVector<QTextLayout::FormatRange> overrides;
+    overrides.reserve(e->attributes().size());
     const int oldPreeditCursor = preeditCursor;
     preeditCursor = e->preeditString().length();
     hideCursor = false;
@@ -2048,7 +2050,7 @@ void QWidgetTextControlPrivate::inputMethodEvent(QInputMethodEvent *e)
             }
         }
     }
-    layout->setAdditionalFormats(overrides);
+    layout->setFormats(overrides);
 
     cursor.endEditBlock();
 
@@ -2138,7 +2140,7 @@ void QWidgetTextControlPrivate::focusEvent(QFocusEvent *e)
 #ifdef QT_KEYPAD_NAVIGATION
         if (!QApplication::keypadNavigationEnabled() || (hasEditFocus && (e->reason() == Qt::PopupFocusReason))) {
 #endif
-        cursorOn = (interactionFlags & Qt::TextSelectableByKeyboard);
+        cursorOn = (interactionFlags & (Qt::TextSelectableByKeyboard | Qt::TextEditable));
         if (interactionFlags & Qt::TextEditable) {
             setBlinkingCursorEnabled(true);
         }
@@ -2877,7 +2879,7 @@ void QWidgetTextControlPrivate::commitPreedit()
     QTextBlock block = cursor.block();
     QTextLayout *layout = block.layout();
     layout->setPreeditArea(-1, QString());
-    layout->clearAdditionalFormats();
+    layout->clearFormats();
     cursor.endEditBlock();
 }