The Android navigation soft keys, most notably seen on the last batches of Nexus devices and a few others such as the Xperia Z, are great. Not only do they allow for a sleeker, more minimal front device face; but they also are quite versatile. You can theme them to your liking, they hide or dim when viewing media, and they can adapt to the app you have opened by either showing or omitting the legacy context menu key.
Soft keys, however, are not perfect. While properly coded apps can hide the navigation bar on devices running Ice Cream Sandwich and above and dim them on Honeycomb and up, not every media app or game makes use of this feature. And without a custom ROM with this feature baked in, doing this manually is quite a chore. This is where XDA Forum Member StupidIdea‘s app GMD AutoHide comes in.
GMD AutoHide works by allowing you to hide or auto-hide the navigation bar with a simple swipe from the bottom of the screen. The app also has a few tricks up its sleeve, courtesy of what the developer calls Quick NavBar, where clicking a soft key then hides the navigation bar, and the ability to spoof the presence of the soft keys to the Android system. The app works without making any permanent modifications, so if something goes wrong, a simple reboot should fix the issue.
To go ahead and hide your navigation softkeys, head over to the application thread and give it a whirl._________