x11: Don't crash if a window is on an unmanaged screen

_gdk_x11_display_screen_for_xrootwin() can return NULL. If so, return
NULL from gdk_x11_window_foreign_new_for_display().

https://bugzilla.gnome.org/show_bug.cgi?id=709716

diff --git a/gdk/x11/gdkwindow-x11.c b/gdk/x11/gdkwindow-x11.c
index 6ee7a9602f827a48bd56f6d8fbf86ae44c8aecd3..a8e92b6bec8ad55e6ca3a7ea363577073bb76021 100644 (file)
--- a/gdk/x11/gdkwindow-x11.c
+++ b/gdk/x11/gdkwindow-x11.c
@@ -1229,6 +1229,8 @@ gdk_x11_window_foreign_new_for_display (GdkDisplay *display,
     XFree (children);
 
   screen = _gdk_x11_display_screen_for_xrootwin (display, root);
+  if (screen == NULL)
+    return NULL;
 
   win = _gdk_display_create_window (display);
   win->impl = g_object_new (GDK_TYPE_WINDOW_IMPL_X11, NULL);