[gimp] app: Add run-time check to gimp_dock_columns_get_docks()

[Martin Nordholts <martinn src gnome org>]

commit 64896eed7fd7b04157c01900c2465efcc52b3845
Author: Martin Nordholts <martinn src gnome org>
Date:   Tue Jan 5 10:37:03 2010 +0100

    app: Add run-time check to gimp_dock_columns_get_docks()

 app/widgets/gimpdockcolumns.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/app/widgets/gimpdockcolumns.c b/app/widgets/gimpdockcolumns.c
index ba5be7d..2bc0c3f 100644
--- a/app/widgets/gimpdockcolumns.c
+++ b/app/widgets/gimpdockcolumns.c
@@ -239,5 +239,7 @@ gimp_dock_columns_remove_dock (GimpDockColumns *dock_columns,
 GList *
 gimp_dock_columns_get_docks (GimpDockColumns *dock_columns)
 {
+  g_return_val_if_fail (GIMP_IS_DOCK_COLUMNS (dock_columns), NULL);
+
   return dock_columns->p->docks;
 }