code: public void registerFrameParticipant (FrameParticipant participant)
      {
          Object[] nparts = ListUtil.testAndAddRef(_participants, participant);
          if (nparts == null) {
              log.warning("Refusing to add duplicate frame participant! " + participant);
          } else {
              _participants = nparts;
          }
      }
docs: Registers a frame participant. The participant will be given the opportunity to do
  processing and rendering on each frame.