$(function(){
    $('#menu ul > li > ul').hide();
		
		$("#menu ul > li.opened > ul").slideDown(10);
		
    $('#menu ul > li').click(function(){

        if ($('#nav ul:animated').size() == 0) {

            $heading = $(this);
            // create a reference to visible sibling elements
            // so we don't have to keep creating a jQuery object
            $expandedSiblings = $heading.siblings().find('ul:visible');
            if ($expandedSiblings.size() > 0) {
                $expandedSiblings.slideUp(400, function(){
                    $heading.children('ul').slideDown(400);
                });
            }
            else {
                $heading.children('ul').slideDown(400);
            }
        }
    });
});