var normalColor="White";
var highlightColor="#C3C3FF";
var currentnr=1;

function highlight(nr, show) {
  var element = document.getElementById("img"+nr);
  element.style.background = show | currentnr==nr ? highlightColor : normalColor;
  return true;
}

function setBackgroundColor(s, nr) {
  var i = 1;
  element = document.getElementById(s+i);
  while (element) {
    element.style.background = i==nr ? highlightColor : normalColor;
    i++;
    element = document.getElementById(s+i);
  }
}

function setStyle(s, nr) {
  var i = 1;
  element = document.getElementById(s+i);
  while (element) {
    element.className = i==nr ? "active" : "";
    i++;
    element = document.getElementById(s+i);
  }
}

function show(nr) {
  if (currentnr == nr) return;
  currentnr = nr;
  if (document.images) {
    document["picture"].src = pictures[nr-1];
    document["picture"].alt= "";
//    setStyle("img", nr);
    setBackgroundColor("img", nr); // style does not work well in IE
    setStyle("a", nr);
  }
}

function shownext() {
  show(currentnr % pictures.length + 1);
}