function preloadImages(prefix)
{
  if(document.images)
  {
    var argLen = preloadImages.arguments.length;
    var prefix = preloadImages.arguments[0];
    for(var i = 1 ; i<argLen ; ++i)
    {
      var aName = arguments[i];
      self[aName+'-on'] = new Image();
      self[aName+'-on'].src = prefix+aName+'-on.png';
      self[aName+'-off'] = new Image();
      self[aName+'-off'].src = prefix+aName+'-off.png';
    }
  }
}