3 files changed, 18 insertions, 2 deletions
diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 0376ab88ac..57148eb811 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -274,6 +274,7 @@ QWidgetPrivate::QWidgetPrivate(int version)
 #endif
 #ifndef QT_NO_OPENGL
       , renderToTextureReallyDirty(1)
+      , renderToTextureComposeActive(0)
 #endif
 #if defined(Q_OS_WIN)
       , noPaintOnScreen(0)
diff --git a/src/widgets/kernel/qwidget_p.h b/src/widgets/kernel/qwidget_p.h
index 9d4bdc7f89..9681cb03ec 100644
--- a/src/widgets/kernel/qwidget_p.h
+++ b/src/widgets/kernel/qwidget_p.h
@@ -744,6 +744,7 @@ public:
 #endif
 #ifndef QT_NO_OPENGL
     uint renderToTextureReallyDirty : 1;
+    uint renderToTextureComposeActive : 1;
 #endif
 
     // *************************** Platform specific ************************************
diff --git a/src/widgets/kernel/qwidgetbackingstore.cpp b/src/widgets/kernel/qwidgetbackingstore.cpp
index 5d13fb926b..7473dd1dfb 100644
--- a/src/widgets/kernel/qwidgetbackingstore.cpp
+++ b/src/widgets/kernel/qwidgetbackingstore.cpp
@@ -61,6 +61,8 @@ QT_BEGIN_NAMESPACE
 
 extern QRegion qt_dirtyRegion(QWidget *);
 
+Q_GLOBAL_STATIC(QPlatformTextureList, qt_dummy_platformTextureList)
+
 /**
  * Flushes the contents of the \a backingStore into the screen area of \a widget.
  * \a tlwOffset is the position of the top level widget relative to the window surface.
@@ -103,6 +105,20 @@ void QWidgetBackingStore::qt_flush(QWidget *widget, const QRegion &region, QBack
         offset += widget->mapTo(tlw, QPoint());
 
 #ifndef QT_NO_OPENGL
+    const bool compositionWasActive = widget->d_func()->renderToTextureComposeActive;
+    if (!widgetTextures) {
+        widget->d_func()->renderToTextureComposeActive = false;
+        // Detect the case of falling back to the normal flush path when no
+        // render-to-texture widgets are visible anymore. We will force one
+        // last flush to go through the OpenGL-based composition to prevent
+        // artifacts. The next flush after this one will use the normal path.
+        if (compositionWasActive)
+            widgetTextures = qt_dummy_platformTextureList;
+    } else {
+        widget->d_func()->renderToTextureComposeActive = true;
+    }
+
+    // re-test since we may have been forced to this path via the dummy texture list above
     if (widgetTextures) {
         qt_window_private(tlw->windowHandle())->compositing = true;
         widget->window()->d_func()->sendComposeStatus(widget->window(), false);
@@ -978,8 +994,6 @@ static void findAllTextureWidgetsRecursively(QWidget *tlw, QWidget *widget)
     }
 }
 
-Q_GLOBAL_STATIC(QPlatformTextureList, qt_dummy_platformTextureList)
-
 static QPlatformTextureList *widgetTexturesFor(QWidget *tlw, QWidget *widget)
 {
     foreach (QPlatformTextureList *tl, QWidgetPrivate::get(tlw)->topData()->widgetTextures) {