Fixed incorrect reporting of child window geometry in xcb plugin.

We should only query the position for top levels, otherwise trust the
position given in the event.

Change-Id: Ic29f25983af3e2c2f27eeb527c08069435ac938c
Reviewed-by: Laszlo Agocs <laszlo.p.agocs@nokia.com>

src/plugins/platforms/xcb/qxcbwindow.cpp

@@ -1307,7 +1307,7 @@ void QXcbWindow::handleConfigureNotifyEvent(const xcb_configure_notify_event_t *
 {
     bool fromSendEvent = (event->response_type & 0x80);
     QPoint pos(event->x, event->y);
-    if (!fromSendEvent) {
+    if (!parent() && !fromSendEvent) {
         // Do not trust the position, query it instead.
         xcb_translate_coordinates_cookie_t cookie = xcb_translate_coordinates(xcb_connection(), xcb_window(),
                                                                               m_screen->root(), 0, 0);