function showPic (whichpic) {
  if (!document.getElementById) return true;
  document.getElementById('navigation').className = whichpic.className;
  return false;
}
function hidePic (whichpic) {
  if (!document.getElementById) return true;
  document.getElementById('navigation').className = "";
  return false;
}
function prepareGallery() {
  if (!document.getElementsByTagName) return false;
  if (!document.getElementById) return false;
  if (!document.getElementById("navigation")) return false;
  var gallery = document.getElementById("navigation");
  var links = gallery.getElementsByTagName("a");
  for ( var i=0; i < links.length; i++) {
    links[i].onmouseover = function() {
      return showPic(this);
    }
    links[i].onmouseout = function() {
      return hidePic(this);
    }
  }
}
window.onload=prepareGallery;