Windows: Fix tooltip flicker on GL surfaces

QPlatformWindow::initialGeometry() would assign a default height to
the initial geometry of the QRollEffectClassWindow since it has height
of 0. This causes the obtained geometry to not match and subsequently
a geometry change being sent synchronously.

Introduce a new flag QWindowPrivate::resizeAutomatic similar to the
existing QWindowPrivate::positionAutomatic to prevent assigning a
default size and pass through the geometry as is where required.

Fixes: QTBUG-74176
Change-Id: I70c66490838a2c4dfe200ec86094d28bd984dd03
Reviewed-by: Kati Kankaanpaa <kati.kankaanpaa@qt.io>
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

src/gui/kernel/qplatformwindow.cpp

@@ -708,10 +708,11 @@ QRect QPlatformWindow::initialGeometry(const QWindow *w,
     const QScreen *screen = effectiveScreen(w);
     if (!screen)
         return initialGeometry;
+    const auto *wp = qt_window_private(const_cast<QWindow*>(w));
     QRect rect(QHighDpi::fromNativePixels(initialGeometry, w));
-    rect.setSize(fixInitialSize(rect.size(), w, defaultWidth, defaultHeight));
-    if (qt_window_private(const_cast<QWindow*>(w))->positionAutomatic
-            && w->type() != Qt::Popup) {
+    if (wp->resizeAutomatic)
+        rect.setSize(fixInitialSize(rect.size(), w, defaultWidth, defaultHeight));
+    if (wp->positionAutomatic && w->type() != Qt::Popup) {
         const QRect availableGeometry = screen->availableGeometry();
         // Center unless the geometry ( + unknown window frame) is too large for the screen).
         if (rect.height() < (availableGeometry.height() * 8) / 9

src/gui/kernel/qwindow_p.h

@@ -90,6 +90,7 @@ public:
         , receivedExpose(false)
         , positionPolicy(WindowFrameExclusive)
         , positionAutomatic(true)
+        , resizeAutomatic(true)
         , contentOrientation(Qt::PrimaryOrientation)
         , opacity(qreal(1.0))
         , minimumSize(0, 0)
@@ -155,6 +156,8 @@ public:
     virtual void processSafeAreaMarginsChanged() {};
 
     bool isPopup() const { return (windowFlags & Qt::WindowType_Mask) == Qt::Popup; }
+    void setAutomaticPositionAndResizeEnabled(bool a)
+    { positionAutomatic = resizeAutomatic = a; }
 
     static QWindowPrivate *get(QWindow *window) { return window->d_func(); }
 
@@ -178,6 +181,7 @@ public:
     bool receivedExpose;
     PositionPolicy positionPolicy;
     bool positionAutomatic;
+    bool resizeAutomatic;
     Qt::ScreenOrientation contentOrientation;
     qreal opacity;
     QRegion mask;

src/plugins/platforms/windows/qwindowswindow.cpp

@@ -1132,7 +1132,8 @@ QWindowCreationContext::QWindowCreationContext(const QWindow *w,
     // TODO: No concept of WA_wasMoved yet that would indicate a
     // CW_USEDEFAULT unless set. For now, assume that 0,0 means 'default'
     // for toplevels.
-    if (geometry.isValid()) {
+    if (geometry.isValid()
+        || !qt_window_private(const_cast<QWindow *>(w))->resizeAutomatic) {
         frameX = geometry.x();
         frameY = geometry.y();
         const QMargins effectiveMargins = margins + customMargins;

src/widgets/kernel/qwidget.cpp

@@ -1543,14 +1543,19 @@ void QWidgetPrivate::createTLSysExtra()
             extra->topextra->window->setMaximumSize(QSize(extra->maxw, extra->maxh));
         if (extra->topextra->opacity != 255 && q->isWindow())
             extra->topextra->window->setOpacity(qreal(extra->topextra->opacity) / qreal(255));
+
+        const bool isTipLabel = q->inherits("QTipLabel");
+        const bool isAlphaWidget = !isTipLabel && q->inherits("QAlphaWidget");
 #ifdef Q_OS_WIN
         // Pass on native parent handle for Widget embedded into Active X.
         const QVariant activeXNativeParentHandle = q->property(activeXNativeParentHandleProperty);
         if (activeXNativeParentHandle.isValid())
             extra->topextra->window->setProperty(activeXNativeParentHandleProperty, activeXNativeParentHandle);
-        if (q->inherits("QTipLabel") || q->inherits("QAlphaWidget"))
+        if (isTipLabel || isAlphaWidget)
             extra->topextra->window->setProperty("_q_windowsDropShadow", QVariant(true));
 #endif
+        if (isTipLabel || isAlphaWidget || q->inherits("QRollEffect"))
+            qt_window_private(extra->topextra->window)->setAutomaticPositionAndResizeEnabled(false);
     }
 
 }