[gtk+/overlay] overlay: Fix child_type implementation

[Matthias Clasen <matthiasc src gnome org>]

commit f483fc14940d067baf6a2398c4e31333aee79329
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Jun 10 21:02:05 2011 -0400

    overlay: Fix child_type implementation

 gtk/gtkoverlay.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkoverlay.c b/gtk/gtkoverlay.c
index 0b5f8e8..6d30c5d 100644
--- a/gtk/gtkoverlay.c
+++ b/gtk/gtkoverlay.c
@@ -568,7 +568,10 @@ gtk_overlay_forall (GtkContainer *overlay,
 static GType
 gtk_overlay_child_type (GtkContainer *overlay)
 {
-  return GTK_TYPE_WIDGET;
+  if (overlay->priv->main_widget != NULL)
+    return G_TYPE_NONE;
+  else
+    return GTK_TYPE_WIDGET;
 }
 
 static void