var timeout	= 600;
var closetimer	= 0;
var ddmenuitem	= 0;
function mopen(id){	
	mcancelclosetime();
	if(ddmenuitem) ddmenuitem.style.visibility = 'hidden';
	ddmenuitem = document.getElementById(id);
	ddmenuitem.style.visibility = 'visible';
}
function mclose(){
	if(ddmenuitem) ddmenuitem.style.visibility = 'hidden';
}
function mclosetime(){
	closetimer = window.setTimeout(mclose, timeout);
}
function mcancelclosetime(){
	if(closetimer){
		window.clearTimeout(closetimer);
		closetimer = null;
	}
}

// close layer when click-out
document.onclick = mclose;