Customize your Modernizr download (errors on page)

I have tried this web site today and have run ito "lame code" controlling the
checkboxes to customize download:
http://modernizr.github.com/Modernizr/2.0-beta/

 $("a.toggle-group").live('click', function() {
    var group = $(this).closest(".features");
    var checkbox = $(group).find(':checkbox');
    checkbox.each(function(){
      $(this).attr('checked', !$(this).is(':checked'));
    });
    event.preventDefault();
  });

Please fix otherwise we will end with errors like:
Error: event is not defined

Source File: http://modernizr.github.com/Modernizr/2.0-beta/#
Line: 173