if (document.images){
  aHighlight = new Array();
  aOff = new Array();
}

function highlight(name, src)
{
  if (document.images) {
    if (aHighlight[name] == null) {
      aHighlight[name] = new Image();
    }
    aHighlight[name].src = src;

    if (aOff[name] == null) {
      aOff[name] = new Image();
      aOff[name].src = document.images[name].src;
    }

    document.images[name].src = aHighlight[name].src;
  }
}

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