docs: def _update_recently_opened_state_machines(self):
          """Update the sub menu Open Recent in File menu
  
          Method clean's first all menu items of the sub menu 'recent open', then insert the user menu item to clean
          recent opened state machine paths and finally insert menu items for all elements in recent opened state machines
          list.
          """
          if not self.registered_view:
              return
  
          for item in self.view.sub_menu_open_recently.get_children():
              self.view.sub_menu_open_recently.remove(item)
  
          menu_item = gui_helper_label.create_menu_item("remove invalid paths", constants.ICON_ERASE,
                                                        global_runtime_config.clean_recently_opened_state_machines)
          self.view.sub_menu_open_recently.append(menu_item)
          self.view.sub_menu_open_recently.append(Gtk.SeparatorMenuItem())
  
          for sm_path in global_runtime_config.get_config_value("recently_opened_state_machines", []):
              # define label string
              root_state_name = gui_helper_state_machine.get_root_state_name_of_sm_file_system_path(sm_path)
              if root_state_name is None and not os.path.isdir(sm_path):
                  root_state_name = 'NOT_ACCESSIBLE'
              label_string = "'{0}' in {1}".format(root_state_name, sm_path) if root_state_name is not None else sm_path
  
              # define icon of menu item
              is_in_libs = library_manager.is_os_path_within_library_root_paths(sm_path)
              button_image = constants.SIGN_LIB if is_in_libs else constants.BUTTON_OPEN
  
              # prepare state machine open call_back function
              sm_open_function = partial(self.on_open_activate, path=sm_path)
  
              # create and insert new menu item
              menu_item = gui_helper_label.create_menu_item(label_string, button_image, sm_open_function)
              self.view.sub_menu_open_recently.append(menu_item)
  
          self.view.sub_menu_open_recently.show_all()