In full screen mode parent fragment can obtain focus

In full screen mode parent fragment (the one which created FullScreenDialog) can have focus while FullScreenDialog is shown. That can lead to unpredictable behavior when user uses physical keyboard (e.g. on Android TV devices).

STEPS TO REPRODUCE:
1. Open sample app in emulator.
2. Press 'Open surname dialog'.
3. Press TAB button on physical keyboard 4 times. Type 'test' for example on popup or physical keyboard.
4. Discard dialog. 'test' text will appear on root fragment in 'Insert name' edit box.

There is no such problem when FullScreenDialog created with setFullScreen(false);