[gtk+] GtkMenu: Properly detach menu when the window is detached

[Matthias Clasen <matthiasc src gnome org>]

commit 955c1c7734507bd5ef9b9aa36469948405cf2b81
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu Jul 23 14:34:12 2015 +0800

    GtkMenu: Properly detach menu when the window is detached
    
    Without properly cleaning up GtkMenu private attach state
    (GtkMenuAttachData) when the attached widget is freed, we would end up
    with an invalid pointer to a freed widget. Trying to detach from that
    widget would cause a segmentation fault.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=752761

 gtk/gtkmenu.c |   22 +++++++++++++++++++++-
 1 files changed, 21 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkmenu.c b/gtk/gtkmenu.c
index 2b4203f..b39de7d 100644
--- a/gtk/gtkmenu.c
+++ b/gtk/gtkmenu.c
@@ -1194,6 +1194,18 @@ attach_widget_screen_changed (GtkWidget *attach_widget,
     menu_change_screen (menu, gtk_widget_get_screen (attach_widget));
 }
 
+static void
+menu_toplevel_attached_to (GtkWindow *toplevel, GParamSpec *pspec, GtkMenu *menu)
+{
+  GtkMenuAttachData *data;
+
+  data = g_object_get_data (G_OBJECT (menu), attach_data_key);
+
+  g_return_if_fail (data);
+
+  gtk_menu_detach (menu);
+}
+
 /**
  * gtk_menu_attach_to_widget:
  * @menu: a #GtkMenu
@@ -1250,6 +1262,8 @@ gtk_menu_attach_to_widget (GtkMenu           *menu,
 
   /* Attach the widget to the toplevel window. */
   gtk_window_set_attached_to (GTK_WINDOW (menu->priv->toplevel), attach_widget);
+  g_signal_connect (GTK_WINDOW (menu->priv->toplevel), "notify::attached-to",
+                    G_CALLBACK (menu_toplevel_attached_to), menu);
 
   _gtk_widget_update_parent_muxer (GTK_WIDGET (menu));
 
@@ -1291,10 +1305,12 @@ gtk_menu_get_attach_widget (GtkMenu *menu)
 void
 gtk_menu_detach (GtkMenu *menu)
 {
+  GtkWindow *toplevel;
   GtkMenuAttachData *data;
   GList *list;
 
   g_return_if_fail (GTK_IS_MENU (menu));
+  toplevel = GTK_WINDOW (menu->priv->toplevel);
 
   /* keep this function in sync with gtk_widget_unparent() */
   data = g_object_get_data (G_OBJECT (menu), attach_data_key);
@@ -1306,7 +1322,11 @@ gtk_menu_detach (GtkMenu *menu)
   g_object_set_data (G_OBJECT (menu), I_(attach_data_key), NULL);
 
   /* Detach the toplevel window. */
-  gtk_window_set_attached_to (GTK_WINDOW (menu->priv->toplevel), NULL);
+  g_signal_handlers_disconnect_by_func (toplevel,
+                                        (gpointer) menu_toplevel_attached_to,
+                                        menu);
+  if (gtk_window_get_attached_to (toplevel) == data->attach_widget)
+    gtk_window_set_attached_to (toplevel, NULL);
 
   g_signal_handlers_disconnect_by_func (data->attach_widget,
                                         (gpointer) attach_widget_screen_changed,