var today = new Date();
var zero_date = new Date(0,0,0);
today.setTime(today.getTime() - zero_date.getTime());
var cookie_expire_date = new Date(today.getTime() + 6000);	

		function swap_content(span) {
			if (document.getElementById(span).style.display == "none") {
				document.getElementById(span).style.display = "block";
				set_swap(span);
			} else {
				document.getElementById(span).style.display = "none";
				kill_swap(span);
			}    				
		}
		function set_swap(span) {
		    set_cookie('ROCKNavigation',span,cookie_expire_date);
		}
		function kill_swap(span) {
		    del_cookie('ROCKNavigation');
		}
		function check_swap() {
				swap_content(get_cookie('ROCKNavigation'));
		}
		function get_cookie(name) {
		    var start = document.cookie.indexOf(name+"=");
		    var len = start+name.length+1;
		    if ((!start) && (name != document.cookie.substring(0,name.length))) return null;
		    if (start == -1) return null;
		    var end = document.cookie.indexOf(";",len);
		    if (end == -1) end = document.cookie.length;
		    return unescape(document.cookie.substring(len,end));
		}
		function set_cookie(name,value,expires,path,domain,secure) {
		    document.cookie = name + "=" +escape(value) +
		        ( (expires) ? ";expires=" + expires.toGMTString() : "") +
		        ( (path) ? ";path=" + path : "") + 
		        ( (domain) ? ";domain=" + domain : "") +
		        ( (secure) ? ";secure" : "");
		}
		function del_cookie(name,path,domain) {
		    if (get_cookie(name)) document.cookie = name + "=" +
		       ( (path) ? ";path=" + path : "") +
		       ( (domain) ? ";domain=" + domain : "") +
		       ";expires=Thu, 01-Jan-70 00:00:01 GMT";
		}