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;