Patch tested, and it works good. Thanks! Cheers Udo http://codereview.appspot.com/913045/diff/1/2 File tryton/gui/window/view_form/model/group.py (right): http://codereview.appspot.com/913045/diff/1/2#newcode35 tryton/gui/window/view_form/model/group.py:35: def __get_window(self): Is it needed using double underscore and implicit name mangling here?