[glade] Fixed assertions for selected objects assumed to be widgets in GladeDesignLayout.

[Tristan Van Berkom <tvb src gnome org>]

commit 6e074589f429d14c36a96936d9869450bc0a40fa
Author: Tristan Van Berkom <tristan van berkom gmail com>
Date:   Mon Mar 7 15:59:48 2011 +0900

    Fixed assertions for selected objects assumed to be widgets in GladeDesignLayout.

 gladeui/glade-design-layout.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/gladeui/glade-design-layout.c b/gladeui/glade-design-layout.c
index e322573..73791d3 100644
--- a/gladeui/glade-design-layout.c
+++ b/gladeui/glade-design-layout.c
@@ -236,7 +236,8 @@ glade_project_is_toplevel_active (GladeProject *project, GtkWidget *toplevel)
 
   for (l = glade_project_selection_get (project); l; l = g_list_next (l))
     {
-      if (gtk_widget_is_ancestor (l->data, toplevel)) return TRUE;
+      if (GTK_IS_WIDGET (l->data) && 
+	  gtk_widget_is_ancestor (l->data, toplevel)) return TRUE;
     }
 
   return FALSE;
@@ -682,7 +683,8 @@ glade_design_layout_draw (GtkWidget * widget, cairo_t * cr)
               /* Dont draw selection on toplevels */
               if (child != selection)
                 {
-                  if (gtk_widget_is_ancestor (selection, child))
+                  if (GTK_IS_WIDGET (selection) && 
+		      gtk_widget_is_ancestor (selection, child))
                   {
                     draw_selection (cr, widget, selection, r, g, b);
                     selected = TRUE;