Blurring screen under Activity results in black screen
<p>When I use </p>

<pre><code>getWindow().setFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND,
                WindowManager.LayoutParams.FLAG_BLUR_BEHIND);
</code></pre>

<p>in my <code>Activity</code> I don't get slightly blurred screen under current <code>Activity</code> but completely black one (top <code>Activity</code> is fine). Need to say it is also black in sample which came with SDK. Can somebody suggest how to make it blurry? </p>
