var timeout    = 100;
var closetimer = 0;
var ddmenuitem = 0;

function mainnav_open()
{  mainnav_canceltimer();
   mainnav_close();
   ddmenuitem = $(this).find('ul').css('visibility', 'visible');}

function mainnav_close()
{  if(ddmenuitem) ddmenuitem.css('visibility', 'hidden');}

function mainnav_timer()
{  closetimer = window.setTimeout(mainnav_close, timeout);}

function mainnav_canceltimer()
{  if(closetimer)
   {  window.clearTimeout(closetimer);
      closetimer = null;}}

$(document).ready(function()
{  $('#mainnav > li').bind('mouseover', mainnav_open)
   $('#mainnav > li').bind('mouseout',  mainnav_timer)});

document.onclick = mainnav_close;