var timeout    = 500;
var closetimer = 0;
var ddmenuitem = 0;

function dropdown_open()
{
  dropdown_canceltimer();
  dropdown_close();
  ddmenuitem = $(this).find('ul').css('visibility', 'visible');
}
function dropdown_close()
{
  if(ddmenuitem) ddmenuitem.css('visibility', 'hidden');
}
function dropdown_timer()
{
  closetimer = window.setTimeout(dropdown_close, timeout);
}
function dropdown_canceltimer()
{
  if(closetimer)
  {
    window.clearTimeout(closetimer);
    closetimer = null;
  }
}
$(document).ready(function() {
  $('#dropdown > li').bind('mouseover', dropdown_open)
  $('#dropdown > li').bind('mouseout',  dropdown_timer)
});

document.onclick = dropdown_close;