Highlight the button when the slideshow switches slides

Hi All..

i have the slideshow that works perfectly thanks to help from this forum.. the 3 externally loaded SWFs  rotate with fade in/outf effect on their own as well as per button click. What I would like to add to it is having the the buttons change appearance (Tint or anything) - just to show which slide the user is currently seeing. I'm very new to AS and I would really appreciate is someone would just point me in a direction of where I should place that function. Thanks so much ahead of time - here's my code:

// Attach Music
var req:URLRequest = new URLRequest("squeeak3.mp3");
var sound:Sound = new Sound();
var controller:SoundChannel = new SoundChannel();

var b:Boolean;

if(!b) {
    b=true;

function soundLoaded(event:Event):void
{
    controller = sound.play(0,1000);
   
    play_btn.addEventListener(MouseEvent.CLICK, playSound);
    stop_btn.addEventListener(MouseEvent.CLICK, stopSound);
}

function playSound(event:MouseEvent):void
{
    SoundMixer.stopAll();
    controller = sound.play(0,1000);
}

function stopSound(event:MouseEvent):void
{
    controller.stop();
    SoundMixer.stopAll();
}

sound.addEventListener(Event.COMPLETE, soundLoaded);
sound.load(req);

}

//Import classes for easier use
import fl.transitions.Tween;
import fl.transitions.TweenEvent;
import fl.transitions.easing.*;

//Timer
var tl:MovieClip = this;
var slideDuration:uint = 8000;// or use whatever
var slideTimer:Timer=new Timer(slideDuration,0);
slideTimer.addEventListener(TimerEvent.TIMER,autoAdvanceF);

var previousBtn:SimpleButton;

var btnA:Array = [one_btn,two_btn,three_btn];

function autoAdvanceF(e:TimerEvent):void {
    nextButtonF(previousBtn).dispatchEvent(new MouseEvent(MouseEvent.CLICK));
}

function nextButtonF(btn:SimpleButton):SimpleButton {// use class type of your buttons
    for (var i:uint=0; i<btnA.length; i++) {
        if (btnA==btn) {
            return btnA[(i+1)%btnA.length];
        }
    }
    return null;
}

//Load external SWF into main
var Xpos:Number = 0;
var Ypos:Number = 0;
var loaderA:Array = [];

//Btns universal function (whenver any button is clicked, the loader will be removed

function btnClick(event:MouseEvent):void {
  
    slideTimer.reset();
    slideTimer.start();

    previousBtn = SimpleButton(event.currentTarget);
  
    var loader:Loader = new Loader();
    loaderA.push(loader);
  
    var newSWFRequest:URLRequest = new URLRequest("swfs/" + event.target.name + ".swf");
    loader.contentLoaderInfo.addEventListener(Event.COMPLETE,loadComplete );

    loader.load(newSWFRequest);
    loader.x = Xpos;
    loader.y = Ypos;
    loader.alpha = 0;
    addChildAt(loader,0);
}

var tween:Tween;
function loadComplete(e:Event):void {
    for (var i:int=loaderA.length-2; i>=0; i--) {
        tl["tween_"+i] = new Tween(loaderA, "alpha", None.easeIn, loaderA.alpha, 0, 1, true);
        tl["tween_"+i].addEventListener(TweenEvent.MOTION_FINISH,onMotionFinish);
        //
    }
    e.target.loader.contentLoaderInfo.removeEventListener(Event.COMPLETE, loadComplete);
    tween = new Tween(e.target.loader, "alpha", None.easeIn, 0, 1, 1, true);
}

function onMotionFinish(e:TweenEvent) {
    Loader(e.target.obj).unload();
    removeChild(e.target.obj);
    loaderA.splice(loaderAIndex(Loader(e.target.obj)),1);
    e.target.obj = null;
}

function loaderAIndex(loader:Loader):int{
    for(var i:int=0;i<loaderA.length;i++){
        if(loaderA==loader){
            return i;
        }
    }
    return -1;
}

/// Button Listerners
one_btn.addEventListener(MouseEvent.CLICK,btnClick);
two_btn.addEventListener(MouseEvent.CLICK,btnClick);
three_btn.addEventListener(MouseEvent.CLICK,btnClick);

btnA[0].dispatchEvent(new MouseEvent(MouseEvent.CLICK));