This allows to filter and sort on sql_catalog_related_keys in ListBoxes.

Must be used in conjunction with a PropertySheet property for the accessor
to be generated, which will actually allow display in the ListBox.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@3407 20353a03-c40f-0410-a6d1-a30d3c3de9de