[gtk+/overlay] overlay: add GtkBuilder support

[Matthias Clasen <matthiasc src gnome org>]

commit bb71cec470e52865b876c21986856c4cf0700ef1
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Jun 10 22:22:18 2011 -0400

    overlay: add GtkBuilder support
    
    The only thing we need to add here is a named child slot for
    overlay children. The name of the slot is 'overlay'.

 gtk/gtkoverlay.c |   26 +++++++++++++++++++++++++-
 1 files changed, 25 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkoverlay.c b/gtk/gtkoverlay.c
index 3f39026..bf13560 100644
--- a/gtk/gtkoverlay.c
+++ b/gtk/gtkoverlay.c
@@ -58,7 +58,11 @@ enum
   CHILD_PROP_Y_OFFSET
 };
 
-G_DEFINE_TYPE (GtkOverlay, gtk_overlay, GTK_TYPE_CONTAINER)
+static void gtk_overlay_buildable_init (GtkBuildableIface *iface);
+
+G_DEFINE_TYPE_WITH_CODE (GtkOverlay, gtk_overlay, GTK_TYPE_CONTAINER,
+                         G_IMPLEMENT_INTERFACE (GTK_TYPE_BUILDABLE,
+                                                gtk_overlay_buildable_init))
 
 /* the reason for this is that the main widget doesn't need
  * to set an offset and it doesn't need an extra window
@@ -734,6 +738,26 @@ gtk_overlay_init (GtkOverlay *overlay)
   gtk_widget_set_has_window (GTK_WIDGET (overlay), FALSE);
 }
 
+static void
+gtk_overlay_buildable_add_child (GtkBuildable *buildable,
+                                 GtkBuilder   *builder,
+                                 GObject      *child,
+                                 const gchar  *type)
+{
+  if (type && strcmp (type, "overlay") == 0)
+    gtk_overlay_add (GTK_OVERLAY (buildable), GTK_WIDGET (child));
+  else if (!type)
+    gtk_container_add (GTK_CONTAINER (buildable), GTK_WIDGET (child));
+  else
+    GTK_BUILDER_WARN_INVALID_CHILD_TYPE (buildable, type);
+}
+
+static void
+gtk_overlay_buildable_init (GtkBuildableIface *iface)
+{
+  iface->add_child = gtk_overlay_buildable_add_child;
+}
+
 /**
  * gtk_overlay_new:
  *