var timeout    = 750;
var closetimer = 0;
var dd         = 0;

function dropdown_open() {
  dropdown_canceltimer();
  dropdown_close();
  dd = $(this).find('ul').css('visibility', 'visible');
}

function dropdown_close() {
  if(dd) dd.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;