function clickHandler(e) {
  var subId, sign, subtree;
  var browser= navigator.appName;
  var getver = navigator.appVersion.substring(0, 1);

  if ((browser.substring(0, 9) == "Microsoft") && (getver >= 4))
  {
    sign = window.event.srcElement;

   if (sign.className == "TreeImg")
    {
      subId = sign.id + "_sub";
      subtree = document.all(subId);

      if (!subtree)
      {
      }
      else if (subtree.style.display == "none")
      {
        sign.src = "images/topen.gif";
        subtree.style.display = "";
      }
      else
      {
        sign.src = "images/tclose.gif";
        subtree.style.display = "none";
      }
    }
  }
  else //this is for everything else
  {
    sign = e.target;

   if (sign.className == "TreeImg")
    {
      subId = sign.id + "_sub";
      subtree = document.images(subId);

      if (!subtree)
      {
      }
      else if (subtree.style.display == "none")
      {
        sign.src = "images/topen.gif";
        subtree.style.display = "";
      }
      else
      {
        sign.src = "images/tclose.gif";
        subtree.style.display = "none";
      }
    }
  }  
}

document.onclick = clickHandler;