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;