code: public static void register (String prefix, ObjectActionHandler handler)
      {
          // make sure we know about potential funny business
          if (_oahandlers.containsKey(prefix)) {
              log.warning("Warning! Overwriting previous object action handler registration, all " +
                          "hell could shortly break loose", "prefix", prefix, "handler", handler);
          }
          _oahandlers.put(prefix, handler);
      }
docs: Registers an object action handler which will be called when a user clicks on an object in
  a scene that has an associated action.