[gtk+] Fix Quartz Full Screen Crash.

[John Ralls <jralls src gnome org>]

commit 46d3611052060cfbba7cbcae7b8ec68a41f011dd
Author: Allin Cottrell <cottrell wfu edu>
Date:   Sun Feb 21 16:22:27 2016 -0800

    Fix Quartz Full Screen Crash.

 gdk/quartz/GdkQuartzNSWindow.c |    8 ++++++++
 gdk/quartz/GdkQuartzView.c     |    2 +-
 2 files changed, 9 insertions(+), 1 deletions(-)
---
diff --git a/gdk/quartz/GdkQuartzNSWindow.c b/gdk/quartz/GdkQuartzNSWindow.c
index d485531..e45c632 100644
--- a/gdk/quartz/GdkQuartzNSWindow.c
+++ b/gdk/quartz/GdkQuartzNSWindow.c
@@ -23,6 +23,14 @@
 
 @implementation GdkQuartzNSWindow
 
+- (void)windowWillClose:(NSNotification*)notification
+{
+  // Clears the delegate when window is going to be closed; since EL
+  // Capitan it is possible that the methods of delegate would get
+  // called after the window has been closed.
+  [self setDelegate:nil];
+}
+
 -(BOOL)windowShouldClose:(id)sender
 {
   GdkWindow *window = [[self contentView] gdkWindow];
diff --git a/gdk/quartz/GdkQuartzView.c b/gdk/quartz/GdkQuartzView.c
index cbd7fe5..780b5a3 100644
--- a/gdk/quartz/GdkQuartzView.c
+++ b/gdk/quartz/GdkQuartzView.c
@@ -662,7 +662,7 @@
   GdkWindowImplQuartz *impl = GDK_WINDOW_IMPL_QUARTZ (gdk_window->impl);
   NSRect rect;
 
-  if (!impl->toplevel)
+  if (!impl || !impl->toplevel)
     return;
 
   if (trackingRect)