docs: def _handle_double_click(self, event):
          """ Double click with left mouse button focuses the state and toggles the collapse status"""
          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.tree_store.get_iter(path)
                  state_model = self.tree_store.get_value(iter, self.MODEL_STORAGE_ID)
  
                  # Set focus to StateModel
                  selection = self._selected_sm_model.selection
                  selection.focus = state_model
  
                  # Toggle collapse status if applicable for this kind of state
                  if self.view.row_expanded(path):
                      self.view.collapse_row(path)
                  else:
                      if isinstance(state_model, ContainerStateModel) or \
                                      isinstance(state_model, LibraryStateModel) and self.show_content(state_model):
                          self.view.expand_to_path(path)