function collapse (id,evt) {
	var ul_elm = document.getElementById("ul-"+id);
	var nav_elm = document.getElementById("nav-"+id);

	ul_elm.className = (ul_elm.className == "show")? "hide":"show";
	nav_elm.className = (nav_elm.className == "collapse")? "expand":"collapse";
	
	stop_event(evt);
}
   
function stop_event(e) {
	if (!e) e = window.event;
	(e.stopPropagation) ? e.stopPropagation() : e.cancelBubble = true;
	(e.preventDefault) ? e.preventDefault() : e.returnValue = false;
	return false;
}