ScrollPane doesn't display its content

Question

I created a scrollpane in as3 and set its source to another object, which contains several rows of icons.
The scrollbar in the scrollpane is getting the right length, which means the object was loaded as expected, but the contant is not showing correctly.
I created a Thumbnail class for this file to load and make each individual thumbnail.
Here is my code, the red text is where each thumbnail is loaded:
import fl.containers.UILoader;
import caurina.transitions.*;
import flash.events.Event;
import fl.containers.ScrollPane;
var urlRequest:URLRequest = new URLRequest("pics.xml");
var urlLoader:URLLoader = new URLLoader();
var myXML:XML = new XML();
var xmlList:XMLList;
myXML.ignoreWhitespace = true;
urlLoader.addEventListener(Event.COMPLETE,fileLoaded);
urlLoader.load(urlRequest);
var arrayURL:Array = new Array();
var arrayName:Array = new Array();
var holderArray:Array = new Array();
var nrColumns:uint = 3;
var sprite:Sprite = new Sprite();
addChild(sprite);
var thumb:Thumbnail;
var thumbsHolder:Sprite = new Sprite();
sprite.addChild(thumbsHolder);
var loaderHolder:Sprite = new Sprite();
loaderHolder.graphics.beginFill(0x666666,1);
loaderHolder.graphics.drawRoundRect(0,0,450,340, 20,20);
loaderHolder.graphics.endFill();
loaderHolder.x = 280;
loaderHolder.y = 240;
sprite.addChild(loaderHolder);
var photoLoader:UILoader = new UILoader();
photoLoader.width = 450;
photoLoader.height = 340;
photoLoader.y = 5;
photoLoader.x = 5;
photoLoader.buttonMode = true;
photoLoader.addEventListener(MouseEvent.CLICK,onClickBack);
loaderHolder.addChild(photoLoader);
var scrollPane:ScrollPane=new ScrollPane();
var skin:MovieClip = new MovieClip();
scrollPane.x = 805;
scrollPane.y = 405;
scrollPane.width = 215;
scrollPane.height = 280;
scrollPane.setStyle( "skin", skin );
scrollPane.setStyle( "upSkin", skin );
scrollPane.source = thumbsHolder;
sprite.addChild(scrollPane);
function fileLoaded(event:Event):void
myXML = XML(event.target.data);
xmlList = myXML.children();
for (var i:int=0; i<xmlList.length(); i++)
  var picURL:String = xmlList[i].url;
  var picName:String = xmlList[i].big_url;
  arrayURL.push(picURL);
  arrayName.push(picName);
  holderArray[i] = new Thumbnail(arrayURL[i],i,arrayName[i]);
  holderArray[i].addEventListener(MouseEvent.CLICK,onClick);
  holderArray[i].name = arrayName[i];
  holderArray[i].buttonMode = true;
  if (i<nrColumns)
   holderArray[i].y = 440;
   holderArray[i].x = i * 65 + 840;
  else
   holderArray[i].y = holderArray[i - nrColumns].y + 65;
   holderArray[i].x = holderArray[i - nrColumns].x;
  thumbsHolder.addChild(holderArray[i]);
  scrollPane.update();
function onClick(event:MouseEvent):void
photoLoader.alpha = 0.1;
photoLoader.source = event.currentTarget.name;
photoLoader.addEventListener(Event.COMPLETE, fadeOut);
function fadeOut(event:Event):void
  Tweener.addTween(photoLoader, {alpha:1, time:0.5, transition:"linear"});
function onClickBack(event:MouseEvent):void
  Tweener.addTween(loaderHolder, {alpha:.5, time:2, transition:"linear"});

Answer 1

Bold is about the only text editing feature that works in the current editor panel.  The rest were disabled due to spam-related abuse (addng white text, etc)
I cannot really follow what is going into where and where it is being put (just too lazy to track it down at this time of night), but it sounds like it might be possible that your content is being planted at a location that it is not visible in the scrollpane panel.  The scrollpane is only 215 pixels wide but you have something called a loaderHolder that is being placed at x = 280.  And then elsewhere you have holderArray[i].x = i * 65 + 840;, which is placing it well beyond the 215 width.