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;