code: public void checkFrameParticipation ()
      {
          // Determine whether or not the timer should participate in
          // media ticks
          boolean participate = _host.isShowing();
  
          // Start participating if necessary
          if (participate && !_participating)
          {
              _fmgr.registerFrameParticipant(this);
              _participating = true;
          }
  
          // Stop participating if necessary
          else if (!participate && _participating)
          {
              _fmgr.removeFrameParticipant(this);
              _participating = false;
          }
      }
docs: Check that the frame knows about the timer.