How to load and replace random swfs into same loader on stage?

Question

Hi...this is very simple, but, for some reason escapes me: using AS3 how can a swf load another swf to replace itself in the same loader on the stage, while simultaneously calling a randomizing function in the first frame of the main timeline, to randomize the next swf?
At the end of each swf (called "koan_#.swf") there is the following old AS2 code...it was used to randomly select and then play a swf from koan array:
_root.index++
if(_root.index>_root.koan.length-1){
_root.index=0;
_root.koan.shuffle();
_root.koan_loader_mc.loadMovie(_root.koan[_root.index]);
This code on the first frame of the main timeline loads a random koan swf properly, but, after the koan plays I would like to load a new random koan swf.
function shuffle(a:Array):Array {
var len:Number = a.length-1;
for (var ivar:Number = len; ivar>=0; ivar--) {
  var p:Number = Math.floor(Math.random()*(ivar+1));
  var t = a[ivar];
  a[ivar] = a[p];
  a[p] = t;
return a;
var index:uint = 0;
var koan_loader:Loader = new Loader();
var koan:Array =["swfs/koans/koan_1.swf","swfs/koans/koan_2.swf", "swfs/koans/koan_3.swf", "swfs/koans/koan_4.swf", "swfs/koans/koan_5.swf", "swfs/koans/koan_6.swf", "swfs/koans/koan_7.swf", "swfs/koans/koan_8.swf", "swfs/koans/koan_9.swf", "swfs/koans/koan_10.swf", "swfs/koans/koan_11.swf", "swfs/koans/koan_12.swf"];
koan = shuffle(koan);
koan_loader.load(new URLRequest(koan[index]));
MovieClip(this).koan_loader_mc.addChild(koan_loader);
Thank you very much.  I've tried multiple variations of updated AS2 code but am at my wits end. 

Answer 1

Alright, the bloody forums won't attach the file for some reason, so here is the code:
Copy and paste this code into a text file and save it as InterfaceEvent.as
package {
     import flash.events.Event;
     public class InterfaceEvent extends Event {
          public static const KOAN_FINISHED:String = "koanFinished";
          public function InterfaceEvent(type:String, bubbles:Boolean = false, cancelable:Boolean = false, index:int = -1, item:Object = null) {
               super(type, bubbles, cancelable);
               this.index = index;
               this.item = item;
          public var index:int = -1;
          public var item:Object = null;
          override public function clone():Event {
               return new InterfaceEvent(this.type, this.bubbles, this.cancelable, this.index, this.item);