Modified setListboxDisplayMode: create selection if it does not exist.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@2658 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Form/SelectionTool.py

@@ -641,6 +641,9 @@ class SelectionTool( UniqueObject, SimpleItem ):
       request = REQUEST
       if selection_name is None: selection_name = request.list_selection_name
       selection = self.getSelectionFor(selection_name, REQUEST)
+      if selection is None:
+        selection = Selection()
+        self.setSelectionFor(selection_name,selection,REQUEST=REQUEST)
 
       if listbox_display_mode == 'FlatListMode':
         flat_list_mode = 1