docs: private void mutualTrackDrop() {
  		for( PointTrack t : trackerLeft.getDroppedTracks(null) ) {
  			LeftTrackInfo info = t.getCookie();
  			trackerRight.dropTrack(info.right);
  		}
  		for( PointTrack t : trackerRight.getDroppedTracks(null) ) {
  			RightTrackInfo info = t.getCookie();
  			// a track could be dropped twice here, such requests are ignored by the tracker
  			trackerLeft.dropTrack(info.left);
  		}
  	}