var archive_shown=false;

function show_vd_links() { 
  if(!archive_shown) {
    archive_shown=true;
    xmlHttp=GetXmlHttpObject();
    if (xmlHttp==null) {
      alert ("Your browser does not support AJAX!");
      return;
    } 
    var url="vd_links.html";
    xmlHttp.onreadystatechange=update_vd_links;
    xmlHttp.open("GET",url,true);
    xmlHttp.send(null);
  }
  else {
    archive_shown=false;
    xmlHttp=GetXmlHttpObject();
    if (xmlHttp==null) {
      alert ("Your browser does not support AJAX!");
      return;
    } 
    var url="blanks.html";
    xmlHttp.onreadystatechange=update_vd_links;
    xmlHttp.open("GET",url,true);
    xmlHttp.send(null);
  }
}

function update_vd_links() {
  if (xmlHttp.readyState==4) { 
    document.getElementById("vd_link_archive").innerHTML=xmlHttp.responseText;
  }
}

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;
}