[FlashCodersNY] Adobe AIR newbie question

[geng wang]

I am getting my first "hello world" AIR app running. The instructions
I am using is Chapter 6 at
http://help.adobe.com/en_US/AIR/1.1/devappsflex/devappsflex.pdf

The application is supposed to run with a semi transparent background
for the window. But my running version has an opaque background, which
annoys me. The code is straight forward. I am using Flex Builder 3
(SDK 3.1) but I believe I have Flash Player 10 installed on my
machine. I guess it's either the CSS syntax or the SDK version
compatible issue.

The code is:

<?xml version="1.0" encoding="utf-8"?>
	<mx:WindowedApplication xmlns:mx="http://www.adobe.com/2006/mxml"
layout="absolute"
	title="Hello World">
		<mx:Style>
			WindowedApplication
			{
				background-color:"0x999999";
				background-alpha:"0.5";
			}
		</mx:Style>
	<mx:Label text="Hello AIR" horizontalCenter="0" verticalCenter="0"/>
</mx:WindowedApplication>

Thanks.