Client: Remove windows from keyboard focus list when destroyed

This fixes the undefined behavior in tst_WaylandClient::touchDrag and mouseDrag

Note: The test still fails if run twice in a row, but it appears to be
deterministic.

Task-number: QTBUG-56187
Change-Id: Ib45d82224f004d1324f2ce4d6b7df05ee36c04f5
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>
(cherry picked from commit 0049240a)
Reviewed-by: Johan Helsing <johan.helsing@qt.io>

src/client/qwaylanddisplay.cpp

@@ -421,6 +421,12 @@ void QWaylandDisplay::handleKeyboardFocusChanged(QWaylandInputDevice *inputDevic
     mLastKeyboardFocus = keyboardFocus;
 }
 
+void QWaylandDisplay::handleWindowDestroyed(QWaylandWindow *window)
+{
+    if (mActiveWindows.contains(window))
+        handleWindowDeactivated(window);
+}
+
 void QWaylandDisplay::handleWaylandSync()
 {
     // This callback is used to set the window activation because we may get an activate/deactivate

src/client/qwaylanddisplay_p.h

@@ -176,6 +176,7 @@ public:
     void handleWindowActivated(QWaylandWindow *window);
     void handleWindowDeactivated(QWaylandWindow *window);
     void handleKeyboardFocusChanged(QWaylandInputDevice *inputDevice);
+    void handleWindowDestroyed(QWaylandWindow *window);
 
 public slots:
     void blockingReadEvents();
@@ -217,7 +218,7 @@ private:
     uint32_t mLastInputSerial;
     QWaylandInputDevice *mLastInputDevice;
     QPointer<QWaylandWindow> mLastInputWindow;
-    QWaylandWindow *mLastKeyboardFocus;
+    QPointer<QWaylandWindow> mLastKeyboardFocus;
     QVector<QWaylandWindow *> mActiveWindows;
     struct wl_callback *mSyncCallback;
     static const wl_callback_listener syncCallbackListener;

src/client/qwaylandwindow.cpp

@@ -102,6 +102,8 @@ QWaylandWindow::QWaylandWindow(QWindow *window)
 
 QWaylandWindow::~QWaylandWindow()
 {
+    mDisplay->handleWindowDestroyed(this);
+
     delete mWindowDecoration;
 
     if (isInitialized())