Since Api 14 the navigation bar have received different treatment in each APi to improve the behavior and this functional operation. Navigation bar is always present when user interact with a control, a dialog, an admob ad, keyboard and user need a possible way to cancel these operations.
in the gaming and application case there are 3 important cases
FULLSCREEN from start
to use this mode developer must set Heading and Display Status bar OFF, this mode is teh usual to make fullscreen games, nava bar will still appears where is needed.
FULLSCREEN achieve from regular theme and entering in immersive mode
to obtain this, projects having Heading & Display Status Bar ON must execute some actions to hide them in proper order. once entering in immersive mode no more actions are required.
Regular Theme (Action Bar) with immersive mode.
This also start having Heading and Display Status bar ON
Please let me know if you want to test this new version and features
For next beta you can try this example that will show these features
(Does not use until next version)