var timeout	= 150;
	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;