1 files changed, 21 insertions, 1 deletions
diff --git a/src/widgets/kernel/qwidgetbackingstore.cpp b/src/widgets/kernel/qwidgetbackingstore.cpp
index 7c9ac5571c..ecaba584f2 100644
--- a/src/widgets/kernel/qwidgetbackingstore.cpp
+++ b/src/widgets/kernel/qwidgetbackingstore.cpp
@@ -992,8 +992,18 @@ static QPlatformTextureList *widgetTexturesFor(QWidget *tlw, QWidget *widget)
         static bool switchableWidgetComposition =
             QGuiApplicationPrivate::instance()->platformIntegration()
                 ->hasCapability(QPlatformIntegration::SwitchableWidgetComposition);
-        if (!switchableWidgetComposition)
+        if (!switchableWidgetComposition
+// The Windows compositor handles fullscreen OpenGL window specially. Besides
+// having trouble with popups, it also has issues with flip-flopping between
+// OpenGL-based and normal flushing. Therefore, stick with GL for fullscreen
+// windows. (QTBUG-53515)
+#if defined(Q_OS_WIN) && !defined(Q_OS_WINRT) && !defined(Q_OS_WINCE)
+                || tlw->windowState().testFlag(Qt::WindowFullScreen)
+#endif
+                )
+        {
             return qt_dummy_platformTextureList();
+        }
     }
 
     return 0;
@@ -1192,10 +1202,20 @@ void QWidgetBackingStore::doSync()
         // We know for sure that the widget isn't overlapped if 'isMoved' is true.
         if (!wd->isMoved)
             wd->subtractOpaqueSiblings(wd->dirty, &hasDirtySiblingsAbove);
+
+        // Make a copy of the widget's dirty region, to restore it in case there is an opaque
+        // render-to-texture child that completely covers the widget, because otherwise the
+        // render-to-texture child won't be visible, due to its parent widget not being redrawn
+        // with a proper blending mask.
+        const QRegion dirtyBeforeSubtractedOpaqueChildren = wd->dirty;
+
         // Scrolled and moved widgets must draw all children.
         if (!wd->isScrolled && !wd->isMoved)
             wd->subtractOpaqueChildren(wd->dirty, w->rect());
 
+        if (wd->dirty.isEmpty() && wd->textureChildSeen)
+            wd->dirty = dirtyBeforeSubtractedOpaqueChildren;
+
         if (wd->dirty.isEmpty()) {
             resetWidget(w);
             continue;