code: public void register(XEvent event) {
  		Date date = XTimeExtension.instance().extractTimestamp(event);
  		if(date != null) {
  			register(date);
  		}
  	}
docs: Registers the given event, i.e. if it has a timestamp, the
  timestamp boundaries will be potentially adjusted to accomodate
  for inclusion of this event.
  
  @param event Event to be registered.