Client: Fix keyboard focus logic and crash

The previous solution did not check for nullptr before dereferencing, which
caused a crash. Furthermore, it checked the new ShellSurface's
shellManagesActiveState before deciding whether to unfocus the old one.

Task-number: QTBUG-55526
Change-Id: I410b6200a5b7b86806f70970730045a4a25f21db
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

src/plugins/platforms/wayland/qwaylanddisplay.cpp

@@ -399,13 +399,16 @@ void QWaylandDisplay::handleKeyboardFocusChanged(QWaylandInputDevice *inputDevic
 {
     QWaylandWindow *keyboardFocus = inputDevice->keyboardFocus();
 
-    if (!keyboardFocus->shellSurface()->shellManagesActiveState() && mLastKeyboardFocus != keyboardFocus) {
-        if (keyboardFocus)
+    if (mLastKeyboardFocus == keyboardFocus)
+        return;
+
+    if (keyboardFocus && !keyboardFocus->shellManagesActiveState())
         handleWindowActivated(keyboardFocus);
-        if (mLastKeyboardFocus)
+
+    if (mLastKeyboardFocus && !mLastKeyboardFocus->shellManagesActiveState())
         handleWindowDeactivated(mLastKeyboardFocus);
-    }
-    mLastKeyboardFocus = inputDevice->keyboardFocus();
+
+    mLastKeyboardFocus = keyboardFocus;
 }
 
 void QWaylandDisplay::handleWaylandSync()

src/plugins/platforms/wayland/qwaylandwindow.cpp

@@ -500,6 +500,11 @@ QWaylandSubSurface *QWaylandWindow::subSurfaceWindow() const
     return mSubSurfaceWindow;
 }
 
+bool QWaylandWindow::shellManagesActiveState() const
+{
+    return mShellSurface && mShellSurface->shellManagesActiveState();
+}
+
 void QWaylandWindow::handleContentOrientationChange(Qt::ScreenOrientation orientation)
 {
     if (mDisplay->compositorVersion() < 2)

src/plugins/platforms/wayland/qwaylandwindow_p.h

@@ -136,6 +136,8 @@ public:
     QWaylandSubSurface *subSurfaceWindow() const;
     QWaylandScreen *screen() const { return mScreen; }
 
+    bool shellManagesActiveState() const;
+
     void handleContentOrientationChange(Qt::ScreenOrientation orientation) Q_DECL_OVERRIDE;
     void setOrientationMask(Qt::ScreenOrientations mask);