[gtk+/gtk-3-6] gtkmenubutton: set menu to NULL in dispose.

[Paolo Borelli <pborelli src gnome org>]

commit 44b575443d459598478864916814b6bdef3c0a7c
Author: Paolo Borelli <pborelli gnome org>
Date:   Sun Nov 4 12:09:23 2012 +0100

    gtkmenubutton: set menu to NULL in dispose.
    
    Prevent menu to be detached multiple times.

 gtk/gtkmenubutton.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkmenubutton.c b/gtk/gtkmenubutton.c
index b46dd3a..61c2d6a 100644
--- a/gtk/gtkmenubutton.c
+++ b/gtk/gtkmenubutton.c
@@ -926,6 +926,7 @@ gtk_menu_button_dispose (GObject *object)
                                             menu_deactivate_cb,
                                             object);
       gtk_menu_detach (GTK_MENU (priv->popup));
+      priv->popup = NULL;
     }
 
   g_clear_object (&priv->model);