QXcbWindow: use an accessor to get the screen instead of storing it

Applications which construct a window with one screen configuration and show
the window later on after a screen configuration change crash because the
QXcbWindow::m_screen still pointed to the screen present at the time of window
construction. In QXcbWindow::handleConfigureNotifyEvent the m_screen should get
updated with the new screen, but I didn't see that method called in the
scenario outlined. Looking at the other platform backends, I however see that
they take the screen directly from the QPlatformWindow instead of storing the
instance, hence this patch which makes QXcbWindow do the same.

Change-Id: I13759a5939315c3aac36ec6e2c25bd0a6d7b1c35
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/plugins/platforms/xcb/qxcbwindow.h b/src/plugins/platforms/xcb/qxcbwindow.h
index b78bf779d0..63fdb250da 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.h
+++ b/src/plugins/platforms/xcb/qxcbwindow.h
@@ -149,6 +149,8 @@ public:
 
     qreal devicePixelRatio() const Q_DECL_OVERRIDE;
 
+    QXcbScreen *xcbScreen() const;
+
     virtual void create();
     virtual void destroy();
     QPlatformScreen *screenForNativeGeometry(const QRect &newGeometry) const;
@@ -186,8 +188,6 @@ protected:
     void doFocusIn();
     void doFocusOut();
 
-    QXcbScreen *m_screen;
-
     xcb_window_t m_window;
 
     uint m_depth;