[MOBILE s:BusyIndicator] - not hitting the designLayer_layerPropertyChangeHandler Event call back in ActionScript. works for mxml impl

Steps to reproduce:

1) run the app below (add as a component to an Application) through coverage tool
2) click the 'create layer' button which will make visible the 'layer' instance of DesignLayer.
3) note that in code coverage we're not hitting the appropriate call back

<?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"
width="100%" height="100%" >
<s:layout>
<s:VerticalLayout/>
</s:layout>
<fx:Script>
<![CDATA[
import mx.core.DesignLayer;

public function createLayer():void

{ p.designLayer = layer; bi.designLayer = layer; layer.visible = true; dispatchEvent(new Event("TestDone")); }

]]
>
</fx:Script>
<s:Button id="b" label="create layer" x="10" y="10" click="createLayer()"/>
<fx:DesignLayer id="layer" visible="false">
<s:Panel id="p">
<s:layout>
<s:HorizontalLayout/>
</s:layout>
<s:BusyIndicator id="bi"/>
<s:Button label="hide layer" click="layer.visible=!layer.visible"/>
</s:Panel>
</fx:DesignLayer>

</s:Application>

Actual Results:

Expected Results:

Workaround (if any):