Reduce usage of QDesktopWidget to resolve screen properties in QtWidgets

Removes the need to initialize QDesktopWidget, just to look up which
screen a widget would map to, the geometry of a screen, number of
screens, etc.

Change-Id: Ieb153b9ff6d3fba645fc528d6e430e8392f990bf
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@qt.io>
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

26 files changed, 178 insertions, 68 deletions

diff --git a/src/widgets/dialogs/qcolordialog.cpp b/src/widgets/dialogs/qcolordialog.cpp
index f361770c3e..9465575b3b 100644
--- a/src/widgets/dialogs/qcolordialog.cpp
+++ b/src/widgets/dialogs/qcolordialog.cpp
@@ -41,6 +41,7 @@
 
 #include "qapplication.h"
 #include "qdesktopwidget.h"
+#include <private/qdesktopwidget_p.h>
 #include "qdrawutil.h"
 #include "qevent.h"
 #include "qimage.h"
@@ -1698,7 +1699,7 @@ void QColorDialogPrivate::initWidgets()
 #else
     // small displays (e.g. PDAs) cannot fit the full color dialog,
     // so just use the color picker.
-    smallDisplay = (QApplication::desktop()->width() < 480 || QApplication::desktop()->height() < 350);
+    smallDisplay = (QDesktopWidgetPrivate::width() < 480 || QDesktopWidgetPrivate::height() < 350);
     const int lumSpace = topLay->spacing() / 2;
 #endif
 
@@ -1744,7 +1745,7 @@ void QColorDialogPrivate::initWidgets()
     } else {
         // better color picker size for small displays
 #if defined(QT_SMALL_COLORDIALOG)
-        QSize screenSize = QApplication::desktop()->availableGeometry(QCursor::pos()).size();
+        QSize screenSize = QDesktopWidgetPrivate::availableGeometry(QCursor::pos()).size();
         pWidth = pHeight = qMin(screenSize.width(), screenSize.height());
         pHeight -= 20;
         if(screenSize.height() > screenSize.width())
diff --git a/src/widgets/dialogs/qdialog.cpp b/src/widgets/dialogs/qdialog.cpp
index 1cd587b78d..9e62f79a8e 100644
--- a/src/widgets/dialogs/qdialog.cpp
+++ b/src/widgets/dialogs/qdialog.cpp
@@ -50,6 +50,7 @@
 
 #include "qevent.h"
 #include "qdesktopwidget.h"
+#include <private/qdesktopwidget_p.h>
 #include "qapplication.h"
 #include "qlayout.h"
 #include "qsizegrip.h"
@@ -811,13 +812,13 @@ void QDialog::adjustPosition(QWidget* w)
         w = w->window();
     QRect desk;
     if (w) {
-        scrn = QApplication::desktop()->screenNumber(w);
-    } else if (QApplication::desktop()->isVirtualDesktop()) {
-        scrn = QApplication::desktop()->screenNumber(QCursor::pos());
+        scrn = QDesktopWidgetPrivate::screenNumber(w);
+    } else if (QDesktopWidgetPrivate::isVirtualDesktop()) {
+        scrn = QDesktopWidgetPrivate::screenNumber(QCursor::pos());
     } else {
-        scrn = QApplication::desktop()->screenNumber(this);
+        scrn = QDesktopWidgetPrivate::screenNumber(this);
     }
-    desk = QApplication::desktop()->availableGeometry(scrn);
+    desk = QDesktopWidgetPrivate::availableGeometry(scrn);
 
     QWidgetList list = QApplication::topLevelWidgets();
     for (int i = 0; (extraw == 0 || extrah == 0) && i < list.size(); ++i) {
diff --git a/src/widgets/dialogs/qmessagebox.cpp b/src/widgets/dialogs/qmessagebox.cpp
index 6a55f62e53..0693f4bea8 100644
--- a/src/widgets/dialogs/qmessagebox.cpp
+++ b/src/widgets/dialogs/qmessagebox.cpp
@@ -60,6 +60,7 @@
 #include <QtGui/qfont.h>
 #include <QtGui/qfontmetrics.h>
 #include <QtGui/qclipboard.h>
+#include <private/qdesktopwidget_p.h>
 
 #ifdef Q_OS_WIN
 #    include <QtCore/qt_windows.h>
@@ -357,7 +358,7 @@ void QMessageBoxPrivate::updateSize()
     if (!q->isVisible())
         return;
 
-    QSize screenSize = QApplication::desktop()->availableGeometry(QCursor::pos()).size();
+    QSize screenSize = QDesktopWidgetPrivate::availableGeometry(QCursor::pos()).size();
     int hardLimit = qMin(screenSize.width() - 480, 1000); // can never get bigger than this
     // on small screens allows the messagebox be the same size as the screen
     if (screenSize.width() <= 1024)
diff --git a/src/widgets/dialogs/qwizard.cpp b/src/widgets/dialogs/qwizard.cpp
index 431447734d..3d9b6a3d62 100644
--- a/src/widgets/dialogs/qwizard.cpp
+++ b/src/widgets/dialogs/qwizard.cpp
@@ -46,6 +46,7 @@
 #include "qboxlayout.h"
 #include "qlayoutitem.h"
 #include "qdesktopwidget.h"
+#include <private/qdesktopwidget_p.h>
 #include "qevent.h"
 #include "qframe.h"
 #include "qlabel.h"
@@ -396,7 +397,7 @@ void QWizardHeader::setup(const QWizardLayoutInfo &info, const QString &title,
         /*
             There is no widthForHeight() function, so we simulate it with a loop.
         */
-        int candidateSubTitleWidth = qMin(512, 2 * QApplication::desktop()->width() / 3);
+        int candidateSubTitleWidth = qMin(512, 2 * QDesktopWidgetPrivate::width() / 3);
         int delta = candidateSubTitleWidth >> 1;
         while (delta > 0) {
             if (subTitleLabel->heightForWidth(candidateSubTitleWidth - delta)
diff --git a/src/widgets/graphicsview/qgraphicsview.cpp b/src/widgets/graphicsview/qgraphicsview.cpp
index 4b7890e9ff..1cc8543fdd 100644
--- a/src/widgets/graphicsview/qgraphicsview.cpp
+++ b/src/widgets/graphicsview/qgraphicsview.cpp
@@ -284,6 +284,7 @@ static const int QGRAPHICSVIEW_PREALLOC_STYLE_OPTIONS = 503; // largest prime <
 #include <QtCore/qscopedvaluerollback.h>
 #include <QtWidgets/qapplication.h>
 #include <QtWidgets/qdesktopwidget.h>
+#include <private/qdesktopwidget_p.h>
 #include <QtGui/qevent.h>
 #include <QtWidgets/qlayout.h>
 #include <QtGui/qtransform.h>
@@ -1248,7 +1249,7 @@ QSize QGraphicsView::sizeHint() const
     if (d->scene) {
         QSizeF baseSize = d->matrix.mapRect(sceneRect()).size();
         baseSize += QSizeF(d->frameWidth * 2, d->frameWidth * 2);
-        return baseSize.boundedTo((3 * QApplication::desktop()->size()) / 4).toSize();
+        return baseSize.boundedTo((3 * QDesktopWidgetPrivate::size()) / 4).toSize();
     }
     return QAbstractScrollArea::sizeHint();
 }
diff --git a/src/widgets/kernel/qdesktopwidget.cpp b/src/widgets/kernel/qdesktopwidget.cpp
index 1e6fbfd239..6077ac38db 100644
--- a/src/widgets/kernel/qdesktopwidget.cpp
+++ b/src/widgets/kernel/qdesktopwidget.cpp
@@ -73,6 +73,11 @@ int QDesktopScreenWidget::screenNumber() const
 
 const QRect QDesktopWidget::screenGeometry(const QWidget *widget) const
 {
+    return QDesktopWidgetPrivate::screenGeometry(widget);
+}
+
+const QRect QDesktopWidgetPrivate::screenGeometry(const QWidget *widget)
+{
     if (Q_UNLIKELY(!widget)) {
         qWarning("QDesktopWidget::screenGeometry(): Attempt "
                  "to get the screen geometry of a null widget");
@@ -86,6 +91,11 @@ const QRect QDesktopWidget::screenGeometry(const QWidget *widget) const
 
 const QRect QDesktopWidget::availableGeometry(const QWidget *widget) const
 {
+    return QDesktopWidgetPrivate::availableGeometry(widget);
+}
+
+const QRect QDesktopWidgetPrivate::availableGeometry(const QWidget *widget)
+{
     if (Q_UNLIKELY(!widget)) {
         qWarning("QDesktopWidget::availableGeometry(): Attempt "
                  "to get the available geometry of a null widget");
@@ -195,16 +205,51 @@ QDesktopWidget::~QDesktopWidget()
 
 bool QDesktopWidget::isVirtualDesktop() const
 {
+    return QDesktopWidgetPrivate::isVirtualDesktop();
+}
+
+bool QDesktopWidgetPrivate::isVirtualDesktop()
+{
     return QGuiApplication::primaryScreen()->virtualSiblings().size() > 1;
 }
 
+QRect QDesktopWidgetPrivate::geometry()
+{
+    return QGuiApplication::primaryScreen()->virtualGeometry();
+}
+
+QSize QDesktopWidgetPrivate::size()
+{
+    return geometry().size();
+}
+
+int QDesktopWidgetPrivate::width()
+{
+    return geometry().width();
+}
+
+int QDesktopWidgetPrivate::height()
+{
+    return geometry().height();
+}
+
 int QDesktopWidget::primaryScreen() const
 {
+    return QDesktopWidgetPrivate::primaryScreen();
+}
+
+int QDesktopWidgetPrivate::primaryScreen()
+{
     return 0;
 }
 
 int QDesktopWidget::numScreens() const
 {
+    return QDesktopWidgetPrivate::numScreens();
+}
+
+int QDesktopWidgetPrivate::numScreens()
+{
     return qMax(QGuiApplication::screens().size(), 1);
 }
 
@@ -218,6 +263,11 @@ QWidget *QDesktopWidget::screen(int screen)
 
 const QRect QDesktopWidget::availableGeometry(int screenNo) const
 {
+    return QDesktopWidgetPrivate::availableGeometry(screenNo);
+}
+
+const QRect QDesktopWidgetPrivate::availableGeometry(int screenNo)
+{
     QList<QScreen *> screens = QGuiApplication::screens();
     if (screenNo == -1)
         screenNo = 0;
@@ -229,6 +279,11 @@ const QRect QDesktopWidget::availableGeometry(int screenNo) const
 
 const QRect QDesktopWidget::screenGeometry(int screenNo) const
 {
+    return QDesktopWidgetPrivate::screenGeometry(screenNo);
+}
+
+const QRect QDesktopWidgetPrivate::screenGeometry(int screenNo)
+{
     QList<QScreen *> screens = QGuiApplication::screens();
     if (screenNo == -1)
         screenNo = 0;
@@ -240,6 +295,11 @@ const QRect QDesktopWidget::screenGeometry(int screenNo) const
 
 int QDesktopWidget::screenNumber(const QWidget *w) const
 {
+    return QDesktopWidgetPrivate::screenNumber(w);
+}
+
+int QDesktopWidgetPrivate::screenNumber(const QWidget *w)
+{
     if (!w)
         return primaryScreen();
 
@@ -287,6 +347,11 @@ int QDesktopWidget::screenNumber(const QWidget *w) const
 
 int QDesktopWidget::screenNumber(const QPoint &p) const
 {
+    return QDesktopWidgetPrivate::screenNumber(p);
+}
+
+int QDesktopWidgetPrivate::screenNumber(const QPoint &p)
+{
     const QList<QScreen *> screens = QGuiApplication::screens();
     if (!screens.isEmpty()) {
         const QList<QScreen *> primaryScreens = screens.first()->virtualSiblings();
diff --git a/src/widgets/kernel/qdesktopwidget_p.h b/src/widgets/kernel/qdesktopwidget_p.h
index dade4fe45e..7a66661771 100644
--- a/src/widgets/kernel/qdesktopwidget_p.h
+++ b/src/widgets/kernel/qdesktopwidget_p.h
@@ -87,6 +87,29 @@ public:
     void _q_availableGeometryChanged();
     QDesktopScreenWidget *widgetForScreen(QScreen *qScreen) const;
 
+    static bool isVirtualDesktop();
+
+    static QRect geometry();
+    static QSize size();
+    static int width();
+    static int height();
+
+    static int numScreens();
+    static int primaryScreen();
+
+    static int screenNumber(const QWidget *widget = nullptr);
+    static int screenNumber(const QPoint &);
+
+    static const QRect screenGeometry(int screen = -1);
+    static const QRect screenGeometry(const QWidget *widget);
+    static const QRect screenGeometry(const QPoint &point)
+    { return screenGeometry(screenNumber(point)); }
+
+    static const QRect availableGeometry(int screen = -1);
+    static const QRect availableGeometry(const QWidget *widget);
+    static const QRect availableGeometry(const QPoint &point)
+    { return availableGeometry(screenNumber(point)); }
+
     QList<QDesktopScreenWidget *> screens;
 };
 
diff --git a/src/widgets/kernel/qtooltip.cpp b/src/widgets/kernel/qtooltip.cpp
index 830a328948..813b64b2dd 100644
--- a/src/widgets/kernel/qtooltip.cpp
+++ b/src/widgets/kernel/qtooltip.cpp
@@ -42,6 +42,7 @@
 
 #include <qapplication.h>
 #include <qdesktopwidget.h>
+#include <private/qdesktopwidget_p.h>
 #include <qevent.h>
 #include <qpointer.h>
 #include <qstyle.h>
@@ -362,10 +363,10 @@ bool QTipLabel::eventFilter(QObject *o, QEvent *e)
 
 int QTipLabel::getTipScreen(const QPoint &pos, QWidget *w)
 {
-    if (QApplication::desktop()->isVirtualDesktop())
-        return QApplication::desktop()->screenNumber(pos);
+    if (QDesktopWidgetPrivate::isVirtualDesktop())
+        return QDesktopWidgetPrivate::screenNumber(pos);
     else
-        return QApplication::desktop()->screenNumber(w);
+        return QDesktopWidgetPrivate::screenNumber(w);
 }
 
 void QTipLabel::placeTip(const QPoint &pos, QWidget *w)
@@ -395,11 +396,11 @@ void QTipLabel::placeTip(const QPoint &pos, QWidget *w)
     extern bool qt_mac_app_fullscreen; //qapplication_mac.mm
     QRect screen;
     if(qt_mac_app_fullscreen)
-        screen = QApplication::desktop()->screenGeometry(getTipScreen(pos, w));
+        screen = QDesktopWidgetPrivate::screenGeometry(getTipScreen(pos, w));
     else
-        screen = QApplication::desktop()->availableGeometry(getTipScreen(pos, w));
+        screen = QDesktopWidgetPrivate::availableGeometry(getTipScreen(pos, w));
 #else
-    QRect screen = QApplication::desktop()->screenGeometry(getTipScreen(pos, w));
+    QRect screen = QDesktopWidgetPrivate::screenGeometry(getTipScreen(pos, w));
 #endif
 
     QPoint p = pos;
diff --git a/src/widgets/kernel/qwhatsthis.cpp b/src/widgets/kernel/qwhatsthis.cpp
index e2cfebb8a1..91d2b503e0 100644
--- a/src/widgets/kernel/qwhatsthis.cpp
+++ b/src/widgets/kernel/qwhatsthis.cpp
@@ -42,6 +42,7 @@
 #include "qapplication.h"
 #include <private/qguiapplication_p.h>
 #include "qdesktopwidget.h"
+#include <private/qdesktopwidget_p.h>
 #include "qevent.h"
 #include "qpixmap.h"
 #include "qscreen.h"
@@ -209,7 +210,7 @@ QWhatsThat::QWhatsThat(const QString& txt, QWidget* parent, QWidget *showTextFor
     }
     else
     {
-        int sw = QApplication::desktop()->width() / 3;
+        int sw = QDesktopWidgetPrivate::width() / 3;
         if (sw < 200)
             sw = 200;
         else if (sw > 300)
@@ -582,14 +583,14 @@ void QWhatsThisPrivate::say(QWidget * widget, const QString &text, int x, int y)
     // okay, now to find a suitable location
 
     int scr = (widget ?
-                QApplication::desktop()->screenNumber(widget) :
+                QDesktopWidgetPrivate::screenNumber(widget) :
 #if 0 /* Used to be included in Qt4 for Q_WS_X11 */ && !defined(QT_NO_CURSOR)
                 QCursor::x11Screen()
 #else
-                QApplication::desktop()->screenNumber(QPoint(x,y))
+                QDesktopWidgetPrivate::screenNumber(QPoint(x,y))
 #endif
                );
-    QRect screen = QApplication::desktop()->screenGeometry(scr);
+    QRect screen = QDesktopWidgetPrivate::screenGeometry(scr);
 
     int w = whatsThat->width();
     int h = whatsThat->height();
diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 2b4c70ed2b..4dcee2771b 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -1454,7 +1454,7 @@ void QWidgetPrivate::create_sys(WId window, bool initializeWindow, bool destroyO
         topData()->initialScreenIndex = -1;
         if (screenNumber < 0) {
             screenNumber = q->windowType() != Qt::Desktop
-                ? QApplication::desktop()->screenNumber(q) : 0;
+                ? QDesktopWidgetPrivate::screenNumber(q) : 0;
         }
         win->setScreen(QGuiApplication::screens().value(screenNumber, Q_NULLPTR));
     }
@@ -7162,7 +7162,7 @@ void QWidgetPrivate::fixPosIncludesFrame()
             if (q->testAttribute(Qt::WA_DontShowOnScreen)) {
                 te->posIncludesFrame = 0;
             } else {
-                if (q->windowHandle()) {
+                if (q->windowHandle() && q->windowHandle()->handle()) {
                     updateFrameStrut();
                     if (!q->data->fstrut_dirty) {
                         data.crect.translate(te->frameStrut.x(), te->frameStrut.y());
@@ -7358,7 +7358,7 @@ QByteArray QWidget::saveGeometry() const
     // - Qt 4.8.6 - today, 5.4 - today: Version 2.0, save screen width in addition to check for high DPI scaling.
     quint16 majorVersion = 2;
     quint16 minorVersion = 0;
-    const int screenNumber = QApplication::desktop()->screenNumber(this);
+    const int screenNumber = QDesktopWidgetPrivate::screenNumber(this);
     stream << magicNumber
            << majorVersion
            << minorVersion
@@ -7372,7 +7372,7 @@ QByteArray QWidget::saveGeometry() const
            << qint32(screenNumber)
            << quint8(windowState() & Qt::WindowMaximized)
            << quint8(windowState() & Qt::WindowFullScreen)
-           << qint32(QApplication::desktop()->screenGeometry(screenNumber).width()); // 1.1 onwards
+           << qint32(QDesktopWidgetPrivate::screenGeometry(screenNumber).width()); // 1.1 onwards
     return array;
 }
 
@@ -7438,10 +7438,9 @@ bool QWidget::restoreGeometry(const QByteArray &geometry)
     if (majorVersion > 1)
         stream >> restoredScreenWidth;
 
-    const QDesktopWidget * const desktop = QApplication::desktop();
-    if (restoredScreenNumber >= desktop->numScreens())
-        restoredScreenNumber = desktop->primaryScreen();
-    const qreal screenWidthF = qreal(desktop->screenGeometry(restoredScreenNumber).width());
+    if (restoredScreenNumber >= QDesktopWidgetPrivate::numScreens())
+        restoredScreenNumber = QDesktopWidgetPrivate::primaryScreen();
+    const qreal screenWidthF = qreal(QDesktopWidgetPrivate::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.
     if (restoredScreenWidth) {
@@ -7468,7 +7467,7 @@ bool QWidget::restoreGeometry(const QByteArray &geometry)
                                        .expandedTo(d_func()->adjustedSize()));
     }
 
-    const QRect availableGeometry = desktop->availableGeometry(restoredScreenNumber);
+    const QRect availableGeometry = QDesktopWidgetPrivate::availableGeometry(restoredScreenNumber);
 
     // Modify the restored geometry if we are about to restore to coordinates
     // that would make the window "lost". This happens if:
@@ -7509,7 +7508,7 @@ bool QWidget::restoreGeometry(const QByteArray &geometry)
             // Setting a geometry on an already maximized window causes this to be
             // restored into a broken, half-maximized state, non-resizable state (QTBUG-4397).
             // Move the window in normal state if needed.
-            if (restoredScreenNumber != desktop->screenNumber(this)) {
+            if (restoredScreenNumber != QDesktopWidgetPrivate::screenNumber(this)) {
                 setWindowState(Qt::WindowNoState);
                 setGeometry(restoredNormalGeometry);
             }
@@ -8573,9 +8572,9 @@ QSize QWidgetPrivate::adjustedSize() const
         if (exp & Qt::Vertical)
             s.setHeight(qMax(s.height(), 100));
 #if 0 // Used to be included in Qt4 for Q_WS_X11
-        QRect screen = QApplication::desktop()->screenGeometry(q->x11Info().screen());
+        QRect screen = QDesktopWidgetPrivate::screenGeometry(q->x11Info().screen());
 #else // all others
-        QRect screen = QApplication::desktop()->screenGeometry(q->pos());
+        QRect screen = QDesktopWidgetPrivate::screenGeometry(q->pos());
 #endif
         s.setWidth(qMin(s.width(), screen.width()*2/3));
         s.setHeight(qMin(s.height(), screen.height()*2/3));
@@ -10719,7 +10718,7 @@ void QWidgetPrivate::setParent_sys(QWidget *newparent, Qt::WindowFlags f)
         f |= Qt::Window;
         if (targetScreen == -1) {
             if (parent)
-                targetScreen = QApplication::desktop()->screenNumber(q->parentWidget()->window());
+                targetScreen = QDesktopWidgetPrivate::screenNumber(q->parentWidget()->window());
         }
     }
 
diff --git a/src/widgets/util/qcompleter.cpp b/src/widgets/util/qcompleter.cpp
index 3a1821240e..8b5aa3f2e4 100644
--- a/src/widgets/util/qcompleter.cpp
+++ b/src/widgets/util/qcompleter.cpp
@@ -160,6 +160,7 @@
 #include "QtWidgets/qapplication.h"
 #include "QtGui/qevent.h"
 #include "QtWidgets/qdesktopwidget.h"
+#include <private/qdesktopwidget_p.h>
 #include "QtWidgets/qlineedit.h"
 
 QT_BEGIN_NAMESPACE
@@ -922,7 +923,7 @@ void QCompleterPrivate::_q_autoResizePopup()
 
 void QCompleterPrivate::showPopup(const QRect& rect)
 {
-    const QRect screen = QApplication::desktop()->availableGeometry(widget);
+    const QRect screen = QDesktopWidgetPrivate::availableGeometry(widget);
     Qt::LayoutDirection dir = widget->layoutDirection();
     QPoint pos;
     int rh, w;
diff --git a/src/widgets/util/qsystemtrayicon.cpp b/src/widgets/util/qsystemtrayicon.cpp
index 19c22eca46..fb3782881c 100644
--- a/src/widgets/util/qsystemtrayicon.cpp
+++ b/src/widgets/util/qsystemtrayicon.cpp
@@ -59,6 +59,7 @@
 #include "qgridlayout.h"
 #include "qapplication.h"
 #include "qdesktopwidget.h"
+#include <private/qdesktopwidget_p.h>
 #include "qbitmap.h"
 
 #include <private/qhighdpiscaling_p.h>
@@ -535,7 +536,7 @@ QBalloonTip::QBalloonTip(const QIcon &icon, const QString &title,
     msgLabel->setAlignment(Qt::AlignTop | Qt::AlignLeft);
 
     // smart size for the message label
-    int limit = QApplication::desktop()->availableGeometry(msgLabel).size().width() / 3;
+    int limit = QDesktopWidgetPrivate::availableGeometry(msgLabel).size().width() / 3;
     if (msgLabel->sizeHint().width() > limit) {
         msgLabel->setWordWrap(true);
         if (msgLabel->sizeHint().width() > limit) {
@@ -602,7 +603,7 @@ void QBalloonTip::resizeEvent(QResizeEvent *ev)
 void QBalloonTip::balloon(const QPoint& pos, int msecs, bool showArrow)
 {
     this->showArrow = showArrow;
-    QRect scr = QApplication::desktop()->screenGeometry(pos);
+    QRect scr = QDesktopWidgetPrivate::screenGeometry(pos);
     QSize sh = sizeHint();
     const int border = 1;
     const int ah = 18, ao = 18, aw = 18, rc = 7;
diff --git a/src/widgets/widgets/qcombobox.cpp b/src/widgets/widgets/qcombobox.cpp
index 4679ed95c5..9a375ae420 100644
--- a/src/widgets/widgets/qcombobox.cpp
+++ b/src/widgets/widgets/qcombobox.cpp
@@ -45,6 +45,7 @@
 #include <qlineedit.h>
 #include <qapplication.h>
 #include <qdesktopwidget.h>
+#include <private/qdesktopwidget_p.h>
 #include <qlistview.h>
 #if QT_CONFIG(tableview)
 #include <qtableview.h>
@@ -262,8 +263,8 @@ QRect QComboBoxPrivate::popupGeometry(int screen) const
     if (const QPlatformTheme *theme = QGuiApplicationPrivate::platformTheme())
         useFullScreenForPopupMenu = theme->themeHint(QPlatformTheme::UseFullScreenForPopupMenu).toBool();
     return useFullScreenForPopupMenu ?
-           QApplication::desktop()->screenGeometry(screen) :
-           QApplication::desktop()->availableGeometry(screen);
+           QDesktopWidgetPrivate::screenGeometry(screen) :
+           QDesktopWidgetPrivate::availableGeometry(screen);
 }
 
 bool QComboBoxPrivate::updateHoverControl(const QPoint &pos)
@@ -2607,7 +2608,7 @@ void QComboBox::showPopup()
     QComboBoxPrivateContainer* container = d->viewContainer();
     QRect listRect(style->subControlRect(QStyle::CC_ComboBox, &opt,
                                          QStyle::SC_ComboBoxListBoxPopup, this));
-    QRect screen = d->popupGeometry(QApplication::desktop()->screenNumber(this));
+    QRect screen = d->popupGeometry(QDesktopWidgetPrivate::screenNumber(this));
 
     QPoint below = mapToGlobal(listRect.bottomLeft());
     int belowHeight = screen.bottom() - below.y();
diff --git a/src/widgets/widgets/qdatetimeedit.cpp b/src/widgets/widgets/qdatetimeedit.cpp
index 6d1521c48b..b6ec6b4065 100644
--- a/src/widgets/widgets/qdatetimeedit.cpp
+++ b/src/widgets/widgets/qdatetimeedit.cpp
@@ -42,6 +42,7 @@
 #include <qapplication.h>
 #include <qdatetimeedit.h>
 #include <qdesktopwidget.h>
+#include <private/qdesktopwidget_p.h>
 #include <qdebug.h>
 #include <qevent.h>
 #include <qlineedit.h>
@@ -2516,7 +2517,7 @@ void QDateTimeEditPrivate::positionCalendarPopup()
     pos = q->mapToGlobal(pos);
     pos2 = q->mapToGlobal(pos2);
     QSize size = monthCalendar->sizeHint();
-    QRect screen = QApplication::desktop()->availableGeometry(pos);
+    QRect screen = QDesktopWidgetPrivate::availableGeometry(pos);
     //handle popup falling "off screen"
     if (q->layoutDirection() == Qt::RightToLeft) {
         pos.setX(pos.x()-size.width());
diff --git a/src/widgets/widgets/qdockarealayout.cpp b/src/widgets/widgets/qdockarealayout.cpp
index 5edcbcf4ec..71726eaeee 100644
--- a/src/widgets/widgets/qdockarealayout.cpp
+++ b/src/widgets/widgets/qdockarealayout.cpp
@@ -45,6 +45,7 @@
 #endif
 #include "QtWidgets/qstyle.h"
 #include "QtWidgets/qdesktopwidget.h"
+#include <private/qdesktopwidget_p.h>
 #include "QtWidgets/qapplication.h"
 #include "QtCore/qvariant.h"
 #include "qdockarealayout_p.h"
@@ -3043,11 +3044,10 @@ QSize QDockAreaLayout::minimumSize() const
 QRect QDockAreaLayout::constrainedRect(QRect rect, QWidget* widget)
 {
     QRect desktop;
-    QDesktopWidget *desktopW = QApplication::desktop();
-    if (desktopW->isVirtualDesktop())
-        desktop = desktopW->screenGeometry(rect.topLeft());
+    if (QDesktopWidgetPrivate::isVirtualDesktop())
+        desktop = QDesktopWidgetPrivate::screenGeometry(rect.topLeft());
     else
-        desktop = desktopW->screenGeometry(widget);
+        desktop = QDesktopWidgetPrivate::screenGeometry(widget);
 
     if (desktop.isValid()) {
         rect.setWidth(qMin(rect.width(), desktop.width()));
diff --git a/src/widgets/widgets/qeffects.cpp b/src/widgets/widgets/qeffects.cpp
index 736f2599fe..4dc5939bfb 100644
--- a/src/widgets/widgets/qeffects.cpp
+++ b/src/widgets/widgets/qeffects.cpp
@@ -51,6 +51,8 @@
 #include "qelapsedtimer.h"
 #include "qdebug.h"
 
+#include <private/qdesktopwidget_p.h>
+
 QT_BEGIN_NAMESPACE
 
 /*
@@ -98,7 +100,7 @@ static QAlphaWidget* q_blend = 0;
   Constructs a QAlphaWidget.
 */
 QAlphaWidget::QAlphaWidget(QWidget* w, Qt::WindowFlags f)
-    : QWidget(QApplication::desktop()->screen(QApplication::desktop()->screenNumber(w)), f)
+    : QWidget(QApplication::desktop()->screen(QDesktopWidgetPrivate::screenNumber(w)), f)
 {
 #ifndef Q_OS_WIN
     setEnabled(false);
diff --git a/src/widgets/widgets/qfontcombobox.cpp b/src/widgets/widgets/qfontcombobox.cpp
index f206d01999..1c56c19c8f 100644
--- a/src/widgets/widgets/qfontcombobox.cpp
+++ b/src/widgets/widgets/qfontcombobox.cpp
@@ -47,6 +47,7 @@
 #include <qapplication.h>
 #include <private/qcombobox_p.h>
 #include <QDesktopWidget>
+#include <private/qdesktopwidget_p.h>
 #include <qdebug.h>
 
 QT_BEGIN_NAMESPACE
@@ -540,7 +541,7 @@ bool QFontComboBox::event(QEvent *e)
         QListView *lview = qobject_cast<QListView*>(view());
         if (lview) {
             lview->window()->setFixedWidth(qMin(width() * 5 / 3,
-                               QApplication::desktop()->availableGeometry(lview).width()));
+                               QDesktopWidgetPrivate::availableGeometry(lview).width()));
         }
     }
     return QComboBox::event(e);
diff --git a/src/widgets/widgets/qmdiarea.cpp b/src/widgets/widgets/qmdiarea.cpp
index 31d9ae21ae..43158fa1fd 100644
--- a/src/widgets/widgets/qmdiarea.cpp
+++ b/src/widgets/widgets/qmdiarea.cpp
@@ -168,6 +168,7 @@
 #include <QFontMetrics>
 #include <QStyleOption>
 #include <QDesktopWidget>
+#include <private/qdesktopwidget_p.h>
 #include <QDebug>
 #include <qmath.h>
 #include <private/qlayoutengine_p.h>
@@ -1746,7 +1747,7 @@ QSize QMdiArea::sizeHint() const
     }
     const int scaleFactor = 3 * (nestedCount + 1);
 
-    QSize desktopSize = QApplication::desktop()->size();
+    QSize desktopSize = QDesktopWidgetPrivate::size();
     QSize size(desktopSize.width() * 2 / scaleFactor, desktopSize.height() * 2 / scaleFactor);
     for (QMdiSubWindow *child : d_func()->childWindows) {
         if (!sanityCheck(child, "QMdiArea::sizeHint"))
diff --git a/src/widgets/widgets/qmenu.cpp b/src/widgets/widgets/qmenu.cpp
index 4ee5b169e7..ab89b8a415 100644
--- a/src/widgets/widgets/qmenu.cpp
+++ b/src/widgets/widgets/qmenu.cpp
@@ -75,6 +75,7 @@
 #include <private/qaction_p.h>
 #include <private/qguiapplication_p.h>
 #include <qpa/qplatformtheme.h>
+#include <private/qdesktopwidget_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -100,7 +101,7 @@ class QTornOffMenu : public QMenu
             Q_Q(QTornOffMenu);
             QSize size = menuSize;
             const QPoint p = (!initialized) ? causedMenu->pos() : q->pos();
-            QRect screen = popupGeometry(QApplication::desktop()->screenNumber(p));
+            QRect screen = popupGeometry(QDesktopWidgetPrivate::screenNumber(p));
             const int desktopFrame = q->style()->pixelMetric(QStyle::PM_MenuDesktopFrameWidth, 0, q);
             const int titleBarHeight = q->style()->pixelMetric(QStyle::PM_TitleBarHeight, 0, q);
             if (scroll && (size.height() > screen.height() - titleBarHeight || size.width() > screen.width())) {
@@ -267,9 +268,9 @@ QRect QMenuPrivate::popupGeometry(const QWidget *widget) const
 {
     if (QGuiApplicationPrivate::platformTheme() &&
             QGuiApplicationPrivate::platformTheme()->themeHint(QPlatformTheme::UseFullScreenForPopupMenu).toBool()) {
-        return QApplication::desktop()->screenGeometry(widget);
+        return QDesktopWidgetPrivate::screenGeometry(widget);
     } else {
-        return QApplication::desktop()->availableGeometry(widget);
+        return QDesktopWidgetPrivate::availableGeometry(widget);
     }
 }
 
@@ -278,9 +279,9 @@ QRect QMenuPrivate::popupGeometry(int screen) const
 {
     if (QGuiApplicationPrivate::platformTheme() &&
             QGuiApplicationPrivate::platformTheme()->themeHint(QPlatformTheme::UseFullScreenForPopupMenu).toBool()) {
-        return QApplication::desktop()->screenGeometry(screen);
+        return QDesktopWidgetPrivate::screenGeometry(screen);
     } else {
-        return QApplication::desktop()->availableGeometry(screen);
+        return QDesktopWidgetPrivate::availableGeometry(screen);
     }
 }
 
@@ -2332,7 +2333,7 @@ void QMenu::popup(const QPoint &p, QAction *atAction)
         screen = d->popupGeometry(this);
     else
 #endif
-    screen = d->popupGeometry(QApplication::desktop()->screenNumber(p));
+    screen = d->popupGeometry(QDesktopWidgetPrivate::screenNumber(p));
     d->updateActionRects(screen);
 
     QPoint pos;
@@ -3601,7 +3602,7 @@ void QMenu::internalDelayedPopup()
         screen = d->popupGeometry(this);
     else
 #endif
-    screen = d->popupGeometry(QApplication::desktop()->screenNumber(pos()));
+    screen = d->popupGeometry(QDesktopWidgetPrivate::screenNumber(pos()));
 
     int subMenuOffset = style()->pixelMetric(QStyle::PM_SubMenuOverlap, 0, this);
     const QRect actionRect(d->actionRect(d->currentAction));
diff --git a/src/widgets/widgets/qmenubar.cpp b/src/widgets/widgets/qmenubar.cpp
index fd48058ec3..5284c16ab0 100644
--- a/src/widgets/widgets/qmenubar.cpp
+++ b/src/widgets/widgets/qmenubar.cpp
@@ -60,6 +60,7 @@
 #include <qpa/qplatformtheme.h>
 #include "private/qguiapplication_p.h"
 #include "qpa/qplatformintegration.h"
+#include <private/qdesktopwidget_p.h>
 
 #ifndef QT_NO_MENUBAR
 
@@ -322,7 +323,7 @@ void QMenuBarPrivate::popupAction(QAction *action, bool activateFirst)
         QSize popup_size = activeMenu->sizeHint();
 
         //we put the popup menu on the screen containing the bottom-center of the action rect
-        QRect screenRect = QApplication::desktop()->screenGeometry(pos + QPoint(adjustedActionRect.width() / 2, 0));
+        QRect screenRect = QDesktopWidgetPrivate::screenGeometry(pos + QPoint(adjustedActionRect.width() / 2, 0));
         pos = QPoint(qMax(pos.x(), screenRect.x()), qMax(pos.y(), screenRect.y()));
 
         const bool fitUp = (q->mapToGlobal(adjustedActionRect.topLeft()).y() >= popup_size.height());
@@ -1566,7 +1567,7 @@ QSize QMenuBar::minimumSizeHint() const
     int fw = style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, 0, this);
     int spaceBelowMenuBar = style()->styleHint(QStyle::SH_MainWindow_SpaceBelowMenuBar, 0, this);
     if(as_gui_menubar) {
-        int w = parentWidget() ? parentWidget()->width() : QApplication::desktop()->width();
+        int w = parentWidget() ? parentWidget()->width() : QDesktopWidgetPrivate::width();
         d->calcActionRects(w - (2 * fw), 0);
         for (int i = 0; ret.isNull() && i < d->actions.count(); ++i)
             ret = d->actionRects.at(i).size();
@@ -1618,7 +1619,7 @@ QSize QMenuBar::sizeHint() const
     int fw = style()->pixelMetric(QStyle::PM_MenuBarPanelWidth, 0, this);
     int spaceBelowMenuBar = style()->styleHint(QStyle::SH_MainWindow_SpaceBelowMenuBar, 0, this);
     if(as_gui_menubar) {
-        const int w = parentWidget() ? parentWidget()->width() : QApplication::desktop()->width();
+        const int w = parentWidget() ? parentWidget()->width() : QDesktopWidgetPrivate::width();
         d->calcActionRects(w - (2 * fw), 0);
         for (int i = 0; i < d->actionRects.count(); ++i) {
             const QRect &actionRect = d->actionRects.at(i);
diff --git a/src/widgets/widgets/qpushbutton.cpp b/src/widgets/widgets/qpushbutton.cpp
index e13ea83fd7..3dd6ee9b0a 100644
--- a/src/widgets/widgets/qpushbutton.cpp
+++ b/src/widgets/widgets/qpushbutton.cpp
@@ -40,6 +40,7 @@
 #include "qapplication.h"
 #include "qbitmap.h"
 #include "qdesktopwidget.h"
+#include <private/qdesktopwidget_p.h>
 #if QT_CONFIG(dialog)
 #include <private/qdialog_p.h>
 #endif
@@ -607,7 +608,7 @@ QPoint QPushButtonPrivate::adjustedMenuPosition()
     QPoint globalPos = q->mapToGlobal(rect.topLeft());
     int x = globalPos.x();
     int y = globalPos.y();
-    const QRect availableGeometry = QApplication::desktop()->availableGeometry(q);
+    const QRect availableGeometry = QDesktopWidgetPrivate::availableGeometry(q);
     if (horizontal) {
         if (globalPos.y() + rect.height() + menuSize.height() <= availableGeometry.bottom()) {
             y += rect.height();
diff --git a/src/widgets/widgets/qsizegrip.cpp b/src/widgets/widgets/qsizegrip.cpp
index f0ede5f2ff..85efd680ec 100644
--- a/src/widgets/widgets/qsizegrip.cpp
+++ b/src/widgets/widgets/qsizegrip.cpp
@@ -57,6 +57,7 @@
 #endif
 
 #include <private/qwidget_p.h>
+#include <private/qdesktopwidget_p.h>
 #include <QtWidgets/qabstractscrollarea.h>
 
 QT_BEGIN_NAMESPACE
@@ -314,7 +315,7 @@ void QSizeGrip::mousePressEvent(QMouseEvent * e)
     bool hasVerticalSizeConstraint = true;
     bool hasHorizontalSizeConstraint = true;
     if (tlw->isWindow())
-        availableGeometry = QApplication::desktop()->availableGeometry(tlw);
+        availableGeometry = QDesktopWidgetPrivate::availableGeometry(tlw);
     else {
         const QWidget *tlwParent = tlw->parentWidget();
         // Check if tlw is inside QAbstractScrollArea/QScrollArea.
diff --git a/src/widgets/widgets/qsplashscreen.cpp b/src/widgets/widgets/qsplashscreen.cpp
index d1b59b5196..468fc272b5 100644
--- a/src/widgets/widgets/qsplashscreen.cpp
+++ b/src/widgets/widgets/qsplashscreen.cpp
@@ -41,6 +41,7 @@
 
 #include "qapplication.h"
 #include "qdesktopwidget.h"
+#include <private/qdesktopwidget_p.h>
 #include "qpainter.h"
 #include "qpixmap.h"
 #include "qtextdocument.h"
@@ -282,7 +283,7 @@ void QSplashScreen::setPixmap(const QPixmap &pixmap)
 
     QRect r(QPoint(), d->pixmap.size()  / d->pixmap.devicePixelRatio());
     resize(r.size());
-    move(QApplication::desktop()->screenGeometry().center() - r.center());
+    move(QDesktopWidgetPrivate::screenGeometry().center() - r.center());
     if (isVisible())
         repaint();
 }
diff --git a/src/widgets/widgets/qtabwidget.cpp b/src/widgets/widgets/qtabwidget.cpp
index c496d267b3..fd783da49a 100644
--- a/src/widgets/widgets/qtabwidget.cpp
+++ b/src/widgets/widgets/qtabwidget.cpp
@@ -44,6 +44,7 @@
 #include "qapplication.h"
 #include "qbitmap.h"
 #include "qdesktopwidget.h"
+#include <private/qdesktopwidget_p.h>
 #include "qevent.h"
 #include "qlayout.h"
 #include "qstackedwidget.h"
@@ -829,7 +830,7 @@ QSize QTabWidget::sizeHint() const
     if(usesScrollButtons())
         t = t.boundedTo(QSize(200,200));
     else
-        t = t.boundedTo(QApplication::desktop()->size());
+        t = t.boundedTo(QDesktopWidgetPrivate::size());
 
     QSize sz = basicSize(d->pos == North || d->pos == South, lc, rc, s, t);
 
@@ -897,7 +898,7 @@ int QTabWidget::heightForWidth(int width) const
     if(usesScrollButtons())
         t = t.boundedTo(QSize(200,200));
     else
-        t = t.boundedTo(QApplication::desktop()->size());
+        t = t.boundedTo(QDesktopWidgetPrivate::size());
 
     const bool tabIsHorizontal = (d->pos == North || d->pos == South);
     const int contentsWidth = width - padding.width();
diff --git a/src/widgets/widgets/qtoolbutton.cpp b/src/widgets/widgets/qtoolbutton.cpp
index f2c5814203..60c9c43399 100644
--- a/src/widgets/widgets/qtoolbutton.cpp
+++ b/src/widgets/widgets/qtoolbutton.cpp
@@ -41,6 +41,7 @@
 
 #include <qapplication.h>
 #include <qdesktopwidget.h>
+#include <private/qdesktopwidget_p.h>
 #include <qdrawutil.h>
 #include <qevent.h>
 #include <qicon.h>
@@ -745,7 +746,7 @@ void QToolButtonPrivate::popupTimerDone()
 #endif
     QPoint p;
     const QRect rect = q->rect(); // Find screen via point in case of QGraphicsProxyWidget.
-    QRect screen = QApplication::desktop()->availableGeometry(q->mapToGlobal(rect.center()));
+    QRect screen = QDesktopWidgetPrivate::availableGeometry(q->mapToGlobal(rect.center()));
     QSize sh = ((QToolButton*)(QMenu*)actualMenu)->receivers(SIGNAL(aboutToShow()))? QSize() : actualMenu->sizeHint();
     if (horizontal) {
         if (q->isRightToLeft()) {
diff --git a/src/widgets/widgets/qwidgetresizehandler.cpp b/src/widgets/widgets/qwidgetresizehandler.cpp
index dc7353a6ca..79502cdd26 100644
--- a/src/widgets/widgets/qwidgetresizehandler.cpp
+++ b/src/widgets/widgets/qwidgetresizehandler.cpp
@@ -43,6 +43,7 @@
 #include "qframe.h"
 #include "qapplication.h"
 #include "qdesktopwidget.h"
+#include <private/qdesktopwidget_p.h>
 #include "qcursor.h"
 #include "qsizegrip.h"
 #include "qevent.h"
@@ -258,7 +259,7 @@ void QWidgetResizeHandler::mouseMoveEvent(QMouseEvent *e)
 
     // Workaround for window managers which refuse to move a tool window partially offscreen.
     if (QGuiApplication::platformName() == QLatin1String("xcb")) {
-        const QRect desktop = QApplication::desktop()->availableGeometry(widget);
+        const QRect desktop = QDesktopWidgetPrivate::availableGeometry(widget);
         pp.rx() = qMax(pp.x(), desktop.left());
         pp.ry() = qMax(pp.y(), desktop.top());
         p.rx() = qMin(p.x(), desktop.right());
@@ -379,7 +380,7 @@ void QWidgetResizeHandler::keyPressEvent(QKeyEvent * e)
     switch (e->key()) {
     case Qt::Key_Left:
         pos.rx() -= delta;
-        if (pos.x() <= QApplication::desktop()->geometry().left()) {
+        if (pos.x() <= QDesktopWidgetPrivate::geometry().left()) {
             if (mode == TopLeft || mode == BottomLeft) {
                 moveOffset.rx() += delta;
                 invertedMoveOffset.rx() += delta;
@@ -404,7 +405,7 @@ void QWidgetResizeHandler::keyPressEvent(QKeyEvent * e)
         break;
     case Qt::Key_Right:
         pos.rx() += delta;
-        if (pos.x() >= QApplication::desktop()->geometry().right()) {
+        if (pos.x() >= QDesktopWidgetPrivate::geometry().right()) {
             if (mode == TopRight || mode == BottomRight) {
                 moveOffset.rx() += delta;
                 invertedMoveOffset.rx() += delta;
@@ -429,7 +430,7 @@ void QWidgetResizeHandler::keyPressEvent(QKeyEvent * e)
         break;
     case Qt::Key_Up:
         pos.ry() -= delta;
-        if (pos.y() <= QApplication::desktop()->geometry().top()) {
+        if (pos.y() <= QDesktopWidgetPrivate::geometry().top()) {
             if (mode == TopLeft || mode == TopRight) {
                 moveOffset.ry() += delta;
                 invertedMoveOffset.ry() += delta;
@@ -454,7 +455,7 @@ void QWidgetResizeHandler::keyPressEvent(QKeyEvent * e)
         break;
     case Qt::Key_Down:
         pos.ry() += delta;
-        if (pos.y() >= QApplication::desktop()->geometry().bottom()) {
+        if (pos.y() >= QDesktopWidgetPrivate::geometry().bottom()) {
             if (mode == BottomLeft || mode == BottomRight) {
                 moveOffset.ry() += delta;
                 invertedMoveOffset.ry() += delta;