Flash As3

[Diegoazul]

Tambien podrias unir todo el código en el primer frame de la capa botones (en tu fla original):

stop();


import fl.containers.UILoader;
import fl.controls.TileList;
import flash.net.URLRequest;
import flash.net.URLLoader;
import fl.data.DataProvider;

//Visualizador
var ui:UILoader = new UILoader();
ui.setSize(400,300);
ui.move(45,300);
ui.source="images/01.jpg";
addChild(ui);

//Lista de Fotos
var list:TileList = new TileList();
list.setSize(400,120);
list.move(40,630);
list.columnWidth=150;
list.rowHeight=100;
list.sourceField="thumb";
addChild(list);

//XML
var xml:XML;
var url:URLRequest=new URLRequest("./xml/galeria.xml");
var loader:URLLoader = new URLLoader();
loader.load(url);

//Eventos
function Completar(event) {
var xml:XML=new XML(loader.data);
var dp:DataProvider=new DataProvider(xml);
list.dataProvider=dp;
}
loader.addEventListener(Event.COMPLETE, Completar);

function alCambiar(event) {
ui.source=list.selectedItem.source;
}
list.addEventListener(Event.CHANGE, alCambiar);


ui.visible=false
list.visible=false

btn1.addEventListener(MouseEvent.CLICK, ira1);

function ira1(Event:MouseEvent) :void
{
gotoAndStop(1)
ui.visible=false
list.visible=false

}

btn2.addEventListener(MouseEvent.CLICK, ira2);

function ira2(Event:MouseEvent) :void
{
gotoAndStop(2)
ui.visible=false
list.visible=false
}

btn3.addEventListener(MouseEvent.CLICK, ira3);

function ira3(Event:MouseEvent) :void
{

gotoAndStop(3)
ui.visible=true
list.visible=true

}

btn4.addEventListener(MouseEvent.CLICK, ira4)

function ira4(Event:MouseEvent) :void
{
gotoAndStop(4)
ui.visible=false
list.visible=false

}