var timeout = 500;
var closetimer = 0;
var ddmenuitem = 0;
// open hidden layer
function mopen(id) {
	// cancel close timer
	mcancelclosetime();
	// close old layer
	if(ddmenuitem) ddmenuitem.style.visibility = 'hidden';
	// get new layer and show it
	ddmenuitem = document.getElementById(id);
	ddmenuitem.style.visibility = 'visible';
}
// close showed layer
function mclose(){
	if(ddmenuitem) ddmenuitem.style.visibility = 'hidden';
}
// go close timer
function mclosetime(){
	closetimer = window.setTimeout(mclose, timeout);
} 
// cancel close timer
function mcancelclosetime(){
	if(closetimer){
		window.clearTimeout(closetimer);
		closetimer = null;
	}
}
// close layer when click-out
document.onclick = mclose;

function isIE(){
	return /msie/i.test(navigator.userAgent) && !/opera/i.test(navigator.userAgent);
}