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;