[gtk+] gtkwindow: Enable CSD when windows set a titlebar

[Jasper St. Pierre <jstpierre src gnome org>]

commit 51f229519d07f771fb2ffc51878fe1eae5b5477f
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Wed Aug 21 13:54:16 2013 -0400

    gtkwindow: Enable CSD when windows set a titlebar
    
    https://bugzilla.gnome.org/show_bug.cgi?id=706529

 gtk/gtkwindow.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index e4becaa..129594b 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -207,7 +207,8 @@ struct _GtkWindowPrivate
                                             */
   guint    gravity                   : 5; /* GdkGravity */
   guint    client_decorated          : 1; /* Decorations drawn client-side */
-  guint    custom_title              : 1; /* app-provided titlebar */
+  guint    custom_title              : 1; /* app-provided titlebar if CSD can't
+                                           * be enabled */
   guint    fullscreen                : 1;
   guint    tiled                     : 1;
 
@@ -3543,7 +3544,11 @@ gtk_window_set_titlebar (GtkWindow *window,
 
   unset_titlebar (window);
 
-  priv->custom_title = TRUE;
+  if (gdk_window_supports_csd (window))
+    gdk_window_enable_csd (window);
+  else
+    priv->custom_title = TRUE;
+
   priv->title_box = titlebar;
   gtk_widget_set_parent (priv->title_box, widget);