code: private static void checkActionsInCommon(Actioner actioner, Collection<ActionRef> actions)
      {
          if (actions.isEmpty())
          {
              actions.addAll(actioner.getActions());
          }
          else
          {
              actions.retainAll(actioner.getActions());
          }
      }
docs: Get all actions in common.
  
  @param actioner The current selectable.
  @param actions The collected actions in common.