docs: def register_actions(self, shortcut_manager):
          """Register callback methods for triggered actions in all child controllers.
  
          :param rafcon.gui.shortcut_manager.ShortcutManager shortcut_manager: Shortcut Manager Object holding mappings
              between shortcuts and actions.
          """
          assert isinstance(shortcut_manager, ShortcutManager)
          self.__shortcut_manager = shortcut_manager
  
          for controller in list(self.__child_controllers.values()):
              if controller not in self.__action_registered_controllers:
                  try:
                      controller.register_actions(shortcut_manager)
                  except Exception as e:
                      logger.error("Error while registering action for {0}: {1}".format(controller.__class__.__name__, e))
                  self.__action_registered_controllers.append(controller)