[gtk/wip/chergert/gdk-macos-gl-renderer: 8/26] gl: hold ref to previous context when replacing

[Christian Hergert <chergert src gnome org>]

commit 590a7c40cf3788590b9d7be2f9b5b9d339a5bd75
Author: Christian Hergert <chergert redhat com>
Date:   Wed Oct 21 17:40:39 2020 -0700

    gl: hold ref to previous context when replacing
    
    On macOS, if we don't hold on to this reference we can get
    in a stack overflow condition disposing the GL context.

 gdk/gdkglcontext.c | 8 ++++++++
 1 file changed, 8 insertions(+)
---
diff --git a/gdk/gdkglcontext.c b/gdk/gdkglcontext.c
index 5d73080b9b..a7ea187f28 100644
--- a/gdk/gdkglcontext.c
+++ b/gdk/gdkglcontext.c
@@ -1114,8 +1114,16 @@ gdk_gl_context_make_current (GdkGLContext *context)
 
   if (gdk_display_make_gl_context_current (gdk_draw_context_get_display (GDK_DRAW_CONTEXT (context)), 
context))
     {
+      GdkGLContext *last = g_private_get (&thread_current_context);
+
+      if (last)
+        g_object_ref (last);
+
       g_private_replace (&thread_current_context, g_object_ref (context));
       gdk_gl_context_check_extensions (context);
+
+      if (last)
+        g_object_unref (last);
     }
 }