var timeout    = 500;
var closetimer = 60;
var ddmenuitem = 0;

function main_menu_open()
{  
	main_menu_canceltimer();
	main_menu_close();
	ddmenuitem = $(this).find('ul').css({'visibility':'visible'});
	
}

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

function main_menu_timer()
{  
	closetimer = window.setTimeout(main_menu_close, timeout);
}

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

$(document).ready(function(){  
	$('#main_menu > li').bind('mouseover', main_menu_open);
	$('#main_menu > li').bind('mouseout',  main_menu_timer);
});

document.onclick = main_menu_close;