[gtk+] gdkwindow: Fix potential NULL pointer dereferences in event code

[Philip Withnall <pwithnall src gnome org>]

commit 7b40fdbc2109ed40faff051bcf2c323ffb280741
Author: Philip Withnall <philip withnall collabora co uk>
Date:   Wed Nov 20 17:21:28 2013 +0000

    gdkwindow: Fix potential NULL pointer dereferences in event code
    
    The event code could potentially dereference pointer_info if the
    invariant that ENTER_NOTIFY and LEAVE_NOTIFY events are only emitted on
    devices which have pointers is violated elsewhere.
    
    Found with scan-build.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=712760

 gdk/gdkwindow.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gdk/gdkwindow.c b/gdk/gdkwindow.c
index aa28e4a..186478b 100644
--- a/gdk/gdkwindow.c
+++ b/gdk/gdkwindow.c
@@ -9935,7 +9935,7 @@ _gdk_windowing_got_event (GdkDisplay *display,
       /* We ended up in this window after some (perhaps other clients)
        * grab, so update the toplevel_under_window state
        */
-      if (is_toplevel &&
+      if (pointer_info && is_toplevel &&
           event->type == GDK_ENTER_NOTIFY &&
           event->crossing.mode == GDK_CROSSING_UNGRAB)
         {
@@ -9949,7 +9949,7 @@ _gdk_windowing_got_event (GdkDisplay *display,
     }
 
   /* Track toplevel_under_pointer */
-  if (is_toplevel)
+  if (pointer_info && is_toplevel)
     {
       if (event->type == GDK_ENTER_NOTIFY &&
           event->crossing.detail != GDK_NOTIFY_INFERIOR)