function showTopic(id) {
  var divs = document.getElementsByTagName("div");
  for (var i=0; i<divs.length; i++ ) {
    if (divs[i].className.indexOf("topic") == -1) continue;
    if (divs[i].getAttribute("id") != id) {
      divs[i].style.display = "none";
    } else {
      divs[i].style.display = "block";
    }
  }
}

function prepareFirstTopic() {	
  if (!document.getElementsByTagName) return false;
  if (!document.getElementById) return false;
  if (!document.getElementById("topicsnav")) return false;
  document.getElementById("topic_one").style.display = "block";
  var tnav = document.getElementById("topicsnav");
  var tlinks = tnav.getElementsByTagName("a");
  for (var i=0; i<1; i++ ) {
  		addClass(tlinks[i],"selected");
    }
}

function prepareTopicsNav() {
  if (!document.getElementsByTagName) return false;
  if (!document.getElementById) return false;
  if (!document.getElementById("topicsnav")) return false;
  var nav = document.getElementById("topicsnav");
  var rollovers = nav.getElementsByTagName("a");
  for (var i=0; i<rollovers.length; i++ ) {
    var sectionId = rollovers[i].getAttribute("rel");
    if (!document.getElementById(sectionId)) continue;
    document.getElementById(sectionId).style.display = "none";
    rollovers[i].destination = sectionId;
    rollovers[i].onmouseover = function() {    
      showTopic(this.destination);
	  var nav = document.getElementById("topicsnav");
	  var rollovers = nav.getElementsByTagName("a");
	  for (var i=0; i<rollovers.length; i++ ) {
	  		rollovers[i].className = "";
	    }
      this.className = "selected";
      return false;
    }
  }
}

addLoadEvent(prepareTopicsNav);
addLoadEvent(prepareFirstTopic);