function change_order(rootdir, table, key, ordernr) {
  var result = '';
  try {
    // Moz supports XMLHttpRequest. IE uses ActiveX. 
    // browser detction is bad. object detection works for any browser
    xmlhttp = window.XMLHttpRequest?new XMLHttpRequest():new ActiveXObject('Microsoft.XMLHTTP');
    xmlhttp.open('GET', rootdir + 'common/def/change_order.php?table=' + table + '&id=' + key + '&ordernr=' + ordernr, false);
    xmlhttp.send(null);
    if ((xmlhttp.readyState == 4) && (xmlhttp.status == 200)) {
      result = unescape(xmlhttp.responseText);
    }
  } catch (e) {
   // browser doesn't support ajax. handle however you want
  }
  // return result;
}