// addEvent code
function addEvent(obj, evType, fn) {
  if (obj.addEventListener) {
    obj.addEventListener(evType, fn, false);
    return true;
  } else if (obj.attachEvent) {
    var r = obj.attachEvent("on"+evType, fn);
    return r;
  } else {
    return false;
  }
}

// removeEvent code
function removeEvent(obj, evType, fn) {
  if (obj.removeEventListener) {
    obj.removeEventListener(evType, fn, false);
    return true;
  } else if (obj.detachEvent) {
    var r = obj.detachEvent("on"+evType, fn);
    return r;
  } else {
    return false;
  }
}