ColorPicker draws with dark border

Found in 4.0.0.10845

Steps to reproduce:
1. Compile and run attached MXML file.
2. Open the ColorPicker
3. Observe bottom edge of popup

Actual Results:
Bottom edge of gradient is black

Expected Results:
Bottom edge should be a darker gray, not black.

Workaround (if any):

<?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/halo">

<s:VGroup x="20" y="20" >
<mx:ColorPicker />
<s:Label id="sdkVer" initialize="sdkVer.text = mx_internal::VERSION;" />
</s:VGroup>

</s:Application>