docs: def setNavigationModel( self, model ):
          """
          Sets the navigation model for this edit.
          
          :param      model | <XNavigationModel>
          """
          self._navigationModel = model
          self._completerTree.setModel(model)
          
          if ( model ):
              model.setSeparator(self.separator())
              completer = XNavigationCompleter(model, self)
              self.setCompleter(completer)
              completer.popup().installEventFilter(self)
          else:
              self.setCompleter(None)
          
          self.rebuild()