getting skin not found error on DropDownList componet on Flex 4 nightly builds since about 4 months ago

Steps to reproduce:
1. add a spark DropDownList to mx:Module
2. in <s:Application add an mx:ModuleLoader url=""
3. add module via byte array
eg
theSwf = event.message.body as ByteArray;
theModuleLoader.loadModule(null, theSwf);

Actual Results:
get rutime error cannot find skin

Expected Results:
no runtime error, had no problem from nightly's in the 14xxx but started happening after that, found ugly work around, but now that 4 released this should be fixed

Workaround (if any):
extend DropDownList and add skin in contstuctor, eg ** note also had to remove scroller, same skin issue at runtime

public class BugFixDropDownList extends DropDownList {
public function BugFixDropDownList()

{ super(); setStyle("skinClass", Class(BugFixDropDownListSkin)); }

}
}

<?xml version="1.0" encoding="utf-8"?>
<!--

ADOBE SYSTEMS INCORPORATED
Copyright 2008 Adobe Systems Incorporated
All Rights Reserved.

NOTICE: Adobe permits you to use, modify, and distribute this file
in accordance with the terms of the license agreement accompanying it.

-->
<!--- The default skin class for the Spark DropDownList component.
The skin for the anchor button for a DropDownList component
is defined by the DropDownListButtonSkin class.

<p>In a custom skin class that uses transitions, set the
<code>itemDestructionPolicy</code> property to <code>none</code>
for the PopUpAnchor defined by the popUp property.</p>

@see spark.components.DropDownList
@see spark.skins.spark.DropDownListButtonSkin

@langversion 3.0
@playerversion Flash 10
@playerversion AIR 1.5
@productversion Flex 4
-->
<s:SparkSkin xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:fb="http://ns.adobe.com/flashbuilder/2009" alpha.disabled=".5">

<!-- host component -->
<fx:Metadata>
<![CDATA[
/**

• @copy spark.skins.spark.ApplicationSkin#hostComponent
  */
  [HostComponent("spark.components.DropDownList")]
  ]]
  >
  </fx:Metadata>

<fx:Script fb:purpose="styling">
<![CDATA[

/* Define the content fill items that should be colored by the "contentBackgroundColor" style. */
static private const contentFill:Array = ["bgFill"];

/**

• @private
  */
  override public function get contentItems():Array {return contentFill}

  ;
  /**

• @private
  */
  override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void
  {
  if (getStyle("borderVisible") == false)
  Unknown macro: { if (border) border.visible = false; if (background) { background.left = background.top = background.right = background.bottom = 0; } /* if (scroller) scroller.minViewportInset = 0;*/ }

  else

  Unknown macro: { if (border) border.visible = true; if (background) { background.left = background.top = background.right = background.bottom = 1; } /* if (scroller) scroller.minViewportInset = 1;*/ }

if (dropShadow)
dropShadow.visible = getStyle("dropShadowVisible");

openButton.setStyle("cornerRadius", getStyle("cornerRadius"));

if (borderStroke)

{ borderStroke.color = getStyle("borderColor"); borderStroke.alpha = getStyle("borderAlpha"); }

super.updateDisplayList(unscaledWidth, unscaledHeight);
}
]]
>
</fx:Script>

<s:states>
<s:State name="normal" />
<s:State name="open" />
<s:State name="disabled" />
</s:states>

<!---
The PopUpAnchor control that opens the drop-down list.

<p>In a custom skin class that uses transitions, set the
<code>itemDestructionPolicy</code> property to <code>none</code>.</p>
-->
<s:PopUpAnchor id="popUp" displayPopUp.normal="false" displayPopUp.open="true" includeIn="open"
left="0" right="0" top="0" bottom="0" itemDestructionPolicy="auto"
popUpPosition="below" popUpWidthMatchesAnchorWidth="true">

<!---
This includes borders, background colors, scrollers, and filters.
@copy spark.components.supportClasses.DropDownListBase#dropDown
-->
<s:Group id="dropDown" maxHeight="134" minHeight="22" >

<!--- @private -->
<s:RectangularDropShadow id="dropShadow" blurX="20" blurY="20" alpha="0.45" distance="7"
angle="90" color="#000000" left="0" top="0" right="0" bottom="0"/>

<!--- @private -->
<s:Rect id="border" left="0" right="0" top="0" bottom="0">
<s:stroke>
<!--- border stroke @private -->
<s:SolidColorStroke id="borderStroke" weight="1"/>
</s:stroke>
</s:Rect>

<!-- fill -->
<!--- Defines the appearance of drop-down list's background fill. -->
<s:Rect id="background" left="1" right="1" top="1" bottom="1" >
<s:fill>
<!---
The color of the drop down's background fill.
The default color is 0xFFFFFF.
-->
<s:SolidColor id="bgFill" color="0xFFFFFF" />
</s:fill>
</s:Rect>

<!--- @private -->
<!-- <s:Scroller id="scroller" left="0" top="0" right="0" bottom="0" hasFocusableChildren="false" minViewportInset="1">-->
<!--- @copy spark.components.SkinnableDataContainer#dataGroup-->
<s:DataGroup id="dataGroup" itemRenderer="spark.skins.spark.DefaultItemRenderer">
<s:layout>
<s:VerticalLayout gap="0" horizontalAlign="contentJustify"/>
</s:layout>
</s:DataGroup>
<!-- </s:Scroller>-->
</s:Group>
</s:PopUpAnchor>

<!--- The default skin is DropDownListButtonSkin.
@copy spark.components.supportClasses.DropDownListBase#openButton
@see spark.skins.spark.DropDownListButtonSkin -->
<s:Button id="openButton" left="0" right="0" top="0" bottom="0" focusEnabled="false"
skinClass="spark.skins.spark.DropDownListButtonSkin" />

<!--- @copy spark.components.DropDownList#labelDisplay -->
<s:Label id="labelDisplay" verticalAlign="middle" maxDisplayedLines="1"
mouseEnabled="false" mouseChildren="false"
left="7" right="30" top="2" bottom="2" width="75" verticalCenter="1" />

</s:SparkSkin>