var display_timeout = 0;

$('document').ready(function() {

	// hide all children lists
	$('#top_menu ul li ul').hide();
	$('#top_menu ul li ul').fadeTo('fast', 0.8);
	
	// on hover display child list
	$('#top_menu ul li').hover(
		function() {
			// fade in specific menu
			if(display_timeout != 0) {
				clearTimeout(display_timeout);
			}
 
            // save a reference to 'this' so we can use it in timeout function
			var this_element = $(this);
            display_timeout = setTimeout(function() {
					display_timeout = 0;
					this_element.children('ul').slideDown('fast');
			}, 200);
		},
		function() {
			// hide menu
			if(display_timeout != 0) {
				clearTimeout(display_timeout);
			}	
			$(this).children('ul').slideUp('fast');
		}
	);

});