Is this a s:List bug?

Question

Flash Builder 4
If you have a
<s:List
layout as TileLayout, with a itemRenderer.
click on a button it filters the AC.
adds scroll bar because there are more objects then displayable.
click on button it filters the AC.
removes scroll bar because there are less objects then displayable.
THIS IS WHERE IT GOES weird!
click on a button it filters it.
There are obviously more objects then displayable but the scroll bars don't get re-added !
I have a label bound to the length of the AC to tell me how many are supposed to be showing up.
Spent atleast a full day messing around with this.

Answer 1

<?xml version="1.0" encoding="utf-8"?>
<s:Application 
xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="
library://ns.adobe.com/flex/spark" xmlns:mx="
library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600" creationComplete="onCreationComplete()">
<fx:Script>
<![CDATA[
import mx.collections.ArrayCollection; 
Bindable] 
private var acTest:ArrayCollection 
private var tempArray:Array = [ {city:
'c1', state:'s1', whatever:'a'},{city:
'c2', state:'s1', whatever:'a'},{city:
'c3', state:'s1', whatever:'a'},{city:
'c4', state:'s1', whatever:'a'},{city:
'c5', state:'s1', whatever:'a'},{city:
'c6', state:'s1', whatever:'a'},{city:
'c7', state:'s1', whatever:'a'},{city:
'c8', state:'s1', whatever:'a'},{city:
'c9', state:'s1', whatever:'a'},{city:
'c10', state:'s1', whatever:'a'},{city:
'c11', state:'s2', whatever:'a'},{city:
'c12', state:'s2', whatever:'a'}]; 
private function onCreationComplete():void{
var _acTest:ArrayCollection = new ArrayCollection(tempArray);acTest = _acTest
private var mySearchCriteria:String; 
private function s1Clicked():void{
mySearchCriteria =
"s1"; 
acTest.filterFunction = myFilterFunction;
acTest.refresh();
private function s2Clicked():void{
mySearchCriteria =
"s2"; 
acTest.filterFunction = myFilterFunction;
acTest.refresh();
private function myFilterFunction(obj:Object):Boolean{
return (obj.state == mySearchCriteria);}
]]>
</fx:Script>
 <s:List id="tlTest" dataProvider="{acTest}" visible="true" itemRenderer="renderers.tlAdsRenderer" width="70" height="452" x="64" y="10">  
<s:layout>
 <s:TileLayout/>  
</s:layout>  
</s:List>
 <s:Button x="9" y="519" label="filter S1" click="s1Clicked()"/>
 <s:Button x="113" y="519" label="filter S2" click="s2Clicked()"/>
 <s:Label x="23" y="486" text="RETURN : {acTest.length}"/></s:Application>