Android API Demos 8 Translucent the class is TranslucentActivity.java doesn't do anything

TranslucentActivity.java doesn't do anything. There is no translucence, nothing special about it. It just shows an activity 开发者_如何学编程screen.

This is a question about what is wrong with the sample.

The very next sample, the Translucent Blur sample after this works, the prior screen is burred...

// Have the system blur any windows behind this one.
getWindow().setFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND,
WindowManager.LayoutParams.FLAG_BLUR_BEHIND);

And it shows what it claims to show.

But nothing is done in the TranslucentActivity, about which I am asking.