test if selection is Null for zoom creation

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@3356 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Form/PlanningBox.py

@@ -800,6 +800,9 @@ class PlanningBoxWidget(Widget.Widget):
           selection.edit(sort_on = sort)       
         here.portal_selections.setSelectionFor(selection_name, selection, REQUEST=REQUEST)
         # we check what is the current zoom in order to redefine height & width
+        if selection is None:
+          current_zoom = 1
+        else:
           current_zoom = selection.getZoom()
         current_zoom= float(current_zoom)
         if current_zoom<=1: