var timeout    = 500;
var closetimer = 0;
var ddmenuitem = 0;
function jsddm_open()
{  jsddm_canceltimer();
   jsddm_close();
   ddmenuitem = $(this).find('ul').css('visibility', 'visible');}
function jsddm_close()
{  if(ddmenuitem) ddmenuitem.css('visibility', 'hidden');}
function jsddm_timer()
{  closetimer = window.setTimeout(jsddm_close, timeout);}
function jsddm_canceltimer()
{  if(closetimer)
   {  window.clearTimeout(closetimer);
      closetimer = null;}}
$(document).ready(function()
{  $('#main_menu > ul > li').bind('mouseover', jsddm_open)
   $('#main_menu > ul > li').bind('mouseout',  jsddm_timer)});
document.onclick = jsddm_close;