function get_query_variable(variable) {
		var query = window.location.search.substring(1);
		var vars = query.split("&");
		for (var i=0;i<vars.length;i++) {
			var pair = vars[i].split("=");
			if (pair[0] == variable) {
				return unescape(pair[1].replace(/\+/g, " "));
			}
		} 
		return null;
	} 


	function add_query_variable(url, name, value)
	{
		url += url.indexOf("?") == -1 ? "?" : "&";
		url += name + "=" + escape(value);
		return url;
	}