code: public void registerAction(IDisable actionElement) {
          if (registeredActions == null) {
              registeredActions = new ArrayList<>();
          }
  
          registeredActions.add(actionElement);
          actionElement.setDisabled(isDisabled());
      }
docs: Registers an action element. Action elements implement the Disable interface and are
  automatically enabled/disabled when the owning container is enabled/disabled.
  
  @param actionElement A component implementing the Disable interface.