notebook: Don't crash on drags not coming from a notebook

diff --git a/gtk/gtknotebook.c b/gtk/gtknotebook.c
index 92f7651a2e95aade97554fe70f1bf13dba04502f..d20342b1f2605e54303be6dfbb943b7257e9f8e8 100644 (file)
--- a/gtk/gtknotebook.c
+++ b/gtk/gtknotebook.c
@@ -3359,7 +3359,7 @@ gtk_notebook_drag_drop (GtkDropTarget *dest,
 
   source = drag ? g_object_get_data (G_OBJECT (drag), "gtk-notebook-drag-origin") : NULL;
 
-  if (!gtk_notebook_can_drag_from (self, source, source->priv->cur_page))
+  if (!source || !gtk_notebook_can_drag_from (self, source, source->priv->cur_page))
     return FALSE;
 
   self->priv->mouse_x = x;