Created attachment 339172 [details] [review]
GdkGLContext chain finalize handler

Running this program: 
 
#include <gtk/gtk.h>
 
int
main (int   argc,
      char *argv[])
{
  if (gtk_init_check (&argc, &argv))
    {
      GtkWidget *win  = gtk_window_new (GTK_WINDOW_TOPLEVEL);
      GtkWidget *area = gtk_gl_area_new ();

      gtk_gl_area_set_required_version (GTK_GL_AREA (area), 3, 2);
      gtk_container_add (GTK_CONTAINER (win), area);
      gtk_widget_show_all (win);

      gtk_widget_destroy (win);
    }

  return 0;
}



after setting GOBJECT_DEBUG=objects results in:

**
GLib-GObject:ERROR:gobject.c:3195:g_object_unref: assertion failed: (g_hash_table_lookup (debug_objects_ht, object) == NULL)

inspecting gobject.c, a comment says it is a trap for objects
not chaining finalize handlers and effectively chaining in 
GdkGLContext finalize handler fixes the issue.

https://git.gnome.org/browse/gtk+/tree/gdk/gdkglcontext.c?h=gtk-3-22&id=a1115c05be1a8bc6e3e299e72accbbee12bd77a7#n151

git describe says:

3.22.2-23-g04db216