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;