var xb =
{
  evtHash: [],

  ieGetUniqueID: function(_elem) {
    if (_elem === window) { return 'theWindow'; }
    else if (_elem === document) { return 'theDocument'; }
    else { return _elem.uniqueID; }
  },

  addEvent: function(_elem, _evtName, _fn, _useCapture) {
    if (typeof _elem.addEventListener != 'undefined') {
      if (_evtName == 'mouseenter')
      { _elem.addEventListener('mouseover', xb.mouseEnter(_fn), _useCapture); }
      else if (_evtName == 'mouseleave')
      { _elem.addEventListener('mouseout', xb.mouseEnter(_fn), _useCapture); }
      else
      { _elem.addEventListener(_evtName, _fn, _useCapture); }
    }
    else if (typeof _elem.attachEvent != 'undefined') {
      var key = '{FNKEY::obj_' + xb.ieGetUniqueID(_elem) + '::evt_' + _evtName + '::fn_' + _fn + '}';
      var f = xb.evtHash[key];
      if (typeof f != 'undefined')
      { return; }

      f = function() {
        _fn.call(_elem);
      };

      xb.evtHash[key] = f;
      _elem.attachEvent('on' + _evtName, f);

      // attach unload event to the window to clean up possibly IE memory leaks
      window.attachEvent('onunload', function() {
        _elem.detachEvent('on' + _evtName, f);
      });

      key = null;
      //f = null;   /* DON'T null this out, or we won't be able to detach it */
    }
    else
    { _elem['on' + _evtName] = _fn; }
  },

  removeEvent: function(_elem, _evtName, _fn, _useCapture) {
    if (typeof _elem.removeEventListener != 'undefined')
    { _elem.removeEventListener(_evtName, _fn, _useCapture); }
    else if (typeof _elem.detachEvent != 'undefined') {
      var key = '{FNKEY::obj_' + xb.ieGetUniqueID(_elem) + '::evt' + _evtName + '::fn_' + _fn + '}';
      var f = xb.evtHash[key];
      if (typeof f != 'undefined') {
        _elem.detachEvent('on' + _evtName, f);
        delete xb.evtHash[key];
      }

      key = null;
      //f = null;   /* DON'T null this out, or we won't be able to detach it */
    }
  },

  mouseEnter: function(_pFn) {
    return function(_evt) {
      var relTarget = _evt.relatedTarget;
      if (this == relTarget || xb.isAChildOf(this, relTarget))
      { return; }

      _pFn.call(this, _evt);
    }
  },

  isAChildOf: function(_parent, _child) {
    if (_parent == _child) { return false };

    while (_child && _child != _parent)
    { _child = _child.parentNode; }

    return _child == _parent;
  }
};