function preload(name, normal, highlight)
{
  if (browserOK)
  {
    pics[name] = new Array(2);
    pics[name][0] = new Image();
    pics[name][0].src = normal;
    pics[name][1] = new Image();
    pics[name][1].src = highlight;
  }
}

function on(name)
{
  if (browserOK)
  {
    document.images[name].src = pics[name][1].src;
  }
}

function off(name)
{
  if (browserOK)
  {
    document.images[name].src = pics[name][0].src;
  }
}