code: def on_clear(self, event):
          
          dia = pmag_menu_dialogs.ClearWD(self.parent, self.parent.WD)
          clear = dia.do_clear()
          if clear:
              print('-I- Clear data object')
              self.contribution = cb.Contribution(self.WD, dmodel=self.data_model)
              self.edited = False
docs: initialize window to allow user to empty the working directory