Background Color on Application tag not showing...

Question

I just recently upgraded to the nightly build version # 4.0.0.10045 and the backgroundColor property on the main application tag is no longer rendering the background color. I noticed a new ApplicationSkin.mxml in the spark skins with the following:
<!---
        A rectangle with a solid color fill that forms the background of the application.
        The color of the fill is set to the Application's backgroundColor property.
    -->
    <s:Rect id="backgroundRect" left="0" right="0" top="0" bottom="0"  >
        <s:fill>
            <s:SolidColor color="{getStyle('backgroundColor')}" />
        </s:fill>
    </s:Rect>
However adding a backgroundColor property to the Application tag or in the CSS has not given any results.

Answer 1

Ok it turns out it is not the application tag causing problems, but the halo VBoxes, HBoxes and Viewstacks. It seems I can no longer apply background colors to them at all.
Here's an example:
<mx:VBox id="footerVBox" horizontalAlign="center" verticalGap="-5" paddingBottom="5" paddingTop="0" backgroundColor="0xFF0000" width="600">
     <mx:HBox horizontalGap="1" verticalAlign="middle">
          <mx:Label text="{copyrightSymbol} 2009 SearchIgnite" fontSize="12" color="#003366" />
          <mx:VRule height="12" strokeColor="#003366"/>
          <mx:Label text="{'Version ' + version}" fontSize="12" color="#003366"/>
          <mx:VRule height="12" strokeColor="#003366"/>
          <mx:Label text="Customer Service 888-744-6483" fontSize="12" color="#003366" />
     </mx:HBox>
</mx:VBox>
Is rendering with a white background behind it, obsucring the background color of my application. The backgroundColor style property is not getting applied at all.
Upon rewriting this group as:
<s:Group id="footerVBox" width="100%">
     <s:layout>
          <s:VerticalLayout horizontalAlign="center" paddingBottom="5" paddingTop="5"  />
     </s:layout>
     <s:Group>
          <s:layout>
               <s:HorizontalLayout verticalAlign="middle" />
          </s:layout>
         <s:Label text="{copyrightSymbol} 2009 SearchIgnite" fontSize="12" color="#003366" />
         <mx:VRule height="12" strokeColor="#003366"/>
         <s:Label text="{'Version ' + version}" fontSize="12" color="#003366"/>
         <mx:VRule height="12" strokeColor="#003366"/>
         <s:Label text="Customer Service 888-744-6483" fontSize="12" color="#003366" />
</s:Group>
</s:Group>       
I am able to get the background color of the app to show through. Again I am using build version 4.0.0.10045 and this was not an issue in the previous builds.