Spark TitleWindow looks different when launched via PopUpManager [wait, what?]

Found in 4.0.0.11004

Steps to reproduce:
1. Compile and run atttached MXML file.
2. Observe TitleWindow.
3. Click Button to launch TitleWindow via PopUpManager.
4. Observe THAT TitleWindow.

Actual Results:
They look different (different header colors, at least).

Expected Results:
They should look the same whether used directly on the Display list in MXML or launched via PopUpManager.

Workaround (if any):
n/a

---

<?xml version="1.0" encoding="utf-8"?>
<!-- -->
<s:Application name="Spark_Panel_controlBar_test"
xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/halo">
<s:controlBarContent>
<s:Button id="btn" label="Launch TitleWindow" click="btn_click(event);" />
</s:controlBarContent>

<fx:Script>
<![CDATA[
import mx.events.CloseEvent;
import mx.managers.PopUpManager;

protected function titleWin_close(evt:CloseEvent):void

{ PopUpManager.removePopUp(evt.currentTarget as TitleWindow); }

protected function btn_click(evt:MouseEvent):void

{ PopUpManager.addPopUp(titleWin, this, true); PopUpManager.centerPopUp(titleWin); titleWin.isPopUp = false; }

]]
>
</fx:Script>

<fx:Declarations>
<s:TitleWindow id="titleWin"
title="Spark TitleWindow title"
width="300" height="200"
close="titleWin_close(event);">
<s:List>
<s:dataProvider>
<s:ArrayList source="[Red,Orange,Yellow,Green,Blue]" />
</s:dataProvider>
</s:List>
<s:controlBarContent>
<s:CheckBox label="Spark CheckBox" />
</s:controlBarContent>
</s:TitleWindow>
</fx:Declarations>

<s:HGroup width="90%" height="90%" horizontalCenter="0" verticalCenter="0">
<s:Panel title="Spark Panel title" width="50%" height="100%">
<s:controlBarContent>
<s:Label text="Panel ControlBar content" />
</s:controlBarContent>
</s:Panel>
<s:TitleWindow title="Spark TitleWindow title" width="50%" height="100%">
<s:controlBarContent>
<s:Label text="TitleWindow ControlBar content" />
</s:controlBarContent>
</s:TitleWindow>
</s:HGroup>

</s:Application>