3 files changed, 54 insertions, 0 deletions
diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index 8e98958949..c94ea0922a 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -1814,6 +1814,15 @@ void QWindowPrivate::destroy()
 
     q->setVisible(false);
 
+    // Let subclasses act, typically by doing graphics resource cleaup, when
+    // the window, to which graphics resource may be tied, is going away.
+    //
+    // NB! This is disfunctional when destroy() is invoked from the dtor since
+    // a reimplemented event() will not get called in the subclasses at that
+    // stage. However, the typical QWindow cleanup involves either close() or
+    // going through QWindowContainer, both of which will do an explicit, early
+    // destroy(), which is good here.
+
     QPlatformSurfaceEvent e(QPlatformSurfaceEvent::SurfaceAboutToBeDestroyed);
     QGuiApplication::sendEvent(q, &e);
 
diff --git a/src/widgets/kernel/qwindowcontainer.cpp b/src/widgets/kernel/qwindowcontainer.cpp
index bb25a3a986..7ae63e54b3 100644
--- a/src/widgets/kernel/qwindowcontainer.cpp
+++ b/src/widgets/kernel/qwindowcontainer.cpp
@@ -241,6 +241,14 @@ QWindow *QWindowContainer::containedWindow() const
 QWindowContainer::~QWindowContainer()
 {
     Q_D(QWindowContainer);
+
+    // Call destroy() explicitly first. The dtor would do this too, but
+    // QEvent::PlatformSurface delivery relies on virtuals. Getting
+    // SurfaceAboutToBeDestroyed can be essential for OpenGL, Vulkan, etc.
+    // QWindow subclasses in particular. Keep these working.
+    if (d->window)
+        d->window->destroy();
+
     delete d->window;
 }
 
diff --git a/tests/auto/widgets/kernel/qwindowcontainer/tst_qwindowcontainer.cpp b/tests/auto/widgets/kernel/qwindowcontainer/tst_qwindowcontainer.cpp
index 5e3868ea8f..6ec1b754d0 100644
--- a/tests/auto/widgets/kernel/qwindowcontainer/tst_qwindowcontainer.cpp
+++ b/tests/auto/widgets/kernel/qwindowcontainer/tst_qwindowcontainer.cpp
@@ -37,6 +37,7 @@
 #include <qmainwindow.h>
 #include <qscreen.h>
 #include <qscopedpointer.h>
+#include <qevent.h>
 
 
 class Window : public QWindow
@@ -77,6 +78,7 @@ private slots:
     void testAncestorChange();
     void testDockWidget();
     void testNativeContainerParent();
+    void testPlatformSurfaceEvent();
     void cleanup();
 
 private:
@@ -343,6 +345,41 @@ void tst_QWindowContainer::testNativeContainerParent()
     QTRY_COMPARE(window->parent(), container->windowHandle());
 }
 
+class EventWindow : public QWindow
+{
+public:
+    EventWindow(bool *surfaceDestroyFlag)  : m_surfaceDestroyFlag(surfaceDestroyFlag) { }
+    bool event(QEvent *e) override;
+
+private:
+    bool *m_surfaceDestroyFlag;
+};
+
+bool EventWindow::event(QEvent *e)
+{
+    if (e->type() == QEvent::PlatformSurface) {
+        if (static_cast<QPlatformSurfaceEvent *>(e)->surfaceEventType() == QPlatformSurfaceEvent::SurfaceAboutToBeDestroyed)
+            *m_surfaceDestroyFlag = true;
+    }
+    return QWindow::event(e);
+}
+
+void tst_QWindowContainer::testPlatformSurfaceEvent()
+{
+    // Verify that SurfaceAboutToBeDestroyed is delivered and the
+    // window subclass still gets a chance to process it.
+
+    bool ok = false;
+    QPointer<EventWindow> window(new EventWindow(&ok));
+    window->create();
+    QWidget *container = QWidget::createWindowContainer(window);
+
+    delete container;
+
+    QCOMPARE(window.data(), nullptr);
+    QVERIFY(ok);
+}
+
 QTEST_MAIN(tst_QWindowContainer)
 
 #include "tst_qwindowcontainer.moc"