var xmlHttp=null;
var myPageId=null;
var defaultPage=null;
var savedURL=null;
var selected=null;

function GetXmlHttpObject() {
	var xmlHttp=null;
	try
	  {
	  // Firefox, Opera 8.0+, Safari
	  xmlHttp=new XMLHttpRequest();
	  }
	catch (e)
	  {
	  // Internet Explorer
	  try
	    {
	    xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
	    }
	  catch (e)
	    {
	    xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
	    }
	  }
	return xmlHttp;
}
//menu loading
function menuLoading() {
	document.getElementById("contentText").innerHTML = "<table border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"><tr><td height=\"368\" align=\"center\" valign=\"middle\"><img src=\"img/loading.gif\" /></td></tr></table>";
}
//load page
function loadPage(url,myId) {
	selected=myId;
	if (myId != "") {
		document.getElementById(myId).src = 'img/'+myId+'-over.jpg';
	}
	for (i=1;i<5;i++) {
		if (myId != ('nav_0'+i)) {
			document.getElementById('nav_0'+i).src = 'img/nav_0'+i+'.jpg';
		}
	}
	//save url
	savedURL = url;
	//set default page
	if (defaultPage === null) {
		defaultPage = document.getElementById("contentText").innerHTML;
	}
	menuLoading();
	xmlHttp=GetXmlHttpObject()
	if (xmlHttp==null) {
		alert ("Your browser does not support AJAX!");
		return;
	} 
	url=url+"?sid="+Math.random();
	xmlHttp.onreadystatechange=stateChanged;
	xmlHttp.open("GET",url,true);
	xmlHttp.send(null);
}
//insert response
function stateChanged(url) { 
	if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete") {
		if (savedURL !== 'default') {
			xmlDoc=xmlHttp.responseText;
			//Check for javascript in page
			tagScript = xmlDoc.indexOf("<script>");
			tagEndScript = xmlDoc.indexOf("</script>");
			if (tagScript != -1 && tagEndScript != -1) {
				tagScript += 8;
				scriptInfo = xmlDoc.substring(tagScript,tagEndScript);
				eval(scriptInfo);
			}
			if (document.getElementById("contentText").innerHTML != xmlDoc) {
				document.getElementById("contentText").innerHTML = xmlDoc;
			}
		}else{
			if (document.getElementById("contentText").innerHTML != defaultPage) {
				document.getElementById("contentText").innerHTML = defaultPage;
			}
		}
	}
}