Refresh context menu

def refresh_menu(self):
        """Refresh context menu"""
        data = self.model.get_data()
        index = self.currentIndex()
        condition = (not isinstance(data, (tuple, set))) and index.isValid() \
                    and not self.readonly
        self.edit_action.setEnabled( condition )
        self.remove_action.setEnabled( condition )
        self.insert_action.setEnabled( not self.readonly )
        self.duplicate_action.setEnabled(condition)
        condition_rename = not isinstance(data, (tuple, list, set))
        self.rename_action.setEnabled(condition_rename)
        self.refresh_plot_entries(index)