[libgd] GdStack: return null if there is no visible child

[Paolo Borelli <pborelli src gnome org>]

commit ea1fafa476d2fe06f76b40d082394d630c5a7b90
Author: Paolo Borelli <pborelli gnome org>
Date:   Sat Feb 16 17:05:10 2013 +0100

    GdStack: return null if there is no visible child

 libgd/gd-stack.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/libgd/gd-stack.c b/libgd/gd-stack.c
index 788050b..0d3a1b8 100644
--- a/libgd/gd-stack.c
+++ b/libgd/gd-stack.c
@@ -600,6 +600,7 @@ gd_stack_add (GtkContainer *container,
 {
   gd_stack_add_named (GD_STACK (container), child, NULL);
 }
+
 static void
 gd_stack_remove (GtkContainer *container,
                 GtkWidget    *child)
@@ -701,7 +702,7 @@ gd_stack_get_visible_child (GdStack *stack)
 {
   g_return_val_if_fail (stack != NULL, NULL);
 
-  return stack->priv->visible_child->widget;
+  return stack->priv->visible_child ? stack->priv->visible_child->widget : NULL;
 }
 
 const char *