var DestID;
var OldContent;
var Showing = '';

function makeRequest(url) {
 	http_request = false;

	if (window.XMLHttpRequest) { // Mozilla, Safari,...
			http_request = new XMLHttpRequest();
			if (http_request.overrideMimeType) {
					http_request.overrideMimeType('text/xml');
					// See note below about this line
			}
	} else if (window.ActiveXObject) { // IE
			try {
					http_request = new ActiveXObject("Msxml2.XMLHTTP");
			} catch (e) {
					try {
							http_request = new ActiveXObject("Microsoft.XMLHTTP");
					} catch (e) {}
			}
	}

	if (!http_request) {
			alert ('Giving up :( Cannot create an XMLHTTP instance');
			return false;
	}
	http_request.onreadystatechange = alertContents;
	http_request.open('GET', url, true);
	http_request.send(null);
}

// ==============================
function alertContents() {
	if (http_request.readyState == 4) {
			if (http_request.status == 200) {
				 if (DestID) {
				   document.getElementById(DestID).innerHTML = http_request.responseText;
				 }
			}
	}
}

function ShowPicture (Request, Destination) {
  if (!DestID || Showing != Request) {
    DestID = Destination;
    if (!OldContent)
      OldContent = document.getElementById (Destination).innerHTML;
    Showing = Request;
    makeRequest (Request);
  } else {
    document.getElementById (Destination).innerHTML = OldContent;
    DestID = 0;
    OldContent = '';
    Showing = '';
  }
}

function RunAjax (Request, Destination) {
    DestID = Destination;
    makeRequest (Request);
}