public void addPageListener(PageListener pl) {
		if (pl == null)
			return;
		if (pageListenerList == null) {
			pageListenerList = Collections.synchronizedList(new ArrayList<PageListener>());
			pageListenerList.add(pl);
		} else {
			if (!pageListenerList.contains(pl))
				pageListenerList.add(pl);
		}
	}