event) {
        if (event.isLeftClick())   return 'left';
        if (event.isRightClick())  return 'right';
        if (event.isMiddleClick()) return 'middle';
        return null;
      }
      
      var container = $('ie_legacy_event_support');
      container.show();
      
      container.attachEvent('onmouseup', function(event) {
        if ('stop' in event) container.failed('Custom property already on event! Something weird happened!');
        Event.extend(event);
        log(event);
        if (!