function write_cookie(name, value, hours)
{
	var expire = "";
	if(hours != null)
	{
		expire = new Date((new Date()).getTime() + hours * 3600000);
		expire = "; expires=" + expire.toGMTString();
	}
	document.cookie = name + "=" + escape(value) + expire;
}

write_cookie('wallpaperistres', screen.width+'x'+screen.height, 24);