function mouseOff(name)
  {
    var pos = document.images[name].src.length - 6;
    var base = document.images[name].src.substring(0,pos);
    document.images[name].src = base + '-i.png';
  }

function mouseOn(name)
  {
    var img = document.images[name];
    var pos = img.src.length - name.length - 6;
    if (img.src.substring (pos, img.src.length) == name + "-i.png")
      { img.src = img.src.substring(0,pos) + name + "-a.png"; }
  }