docs: def _handle_double_click(self, event):
          """ Double click with left mouse button focuses the element"""
          if event.get_button()[1] == 1:  # Left mouse button
              path_info = self.tree_view.get_path_at_pos(int(event.x), int(event.y))
              if path_info:  # Valid entry was clicked on
                  path = path_info[0]
                  iter = self.list_store.get_iter(path)
                  model = self.list_store.get_value(iter, self.MODEL_STORAGE_ID)
                  selection = self.model.get_state_machine_m().selection
                  selection.focus = model