I have written before on how Android could be using their software navigation buttons more appropriately. Seeing how Android 5.0 and 5.1 handle screen pinning seems another one of those situations where it could leverage that capability.
For those unaware of the feature, Android 5.0 introduced a feature that allowed you to pin a certain application to the home screen. The primary use case for this feature is to prevent a child or some one you hand over your phone to to accidentally exit an app that you want them to see/use. Since the feature doesn’t require a pin number to exit the app, the feature is not so much designed for security but rather for preventing accidents. Exiting the pinned app requires you to tap the “Back” and the “Overview” screen at the same time. A feature that people may forget (though the OS does bring up a message if you do tap any of the navigation buttons when a screen is pinned). This is probably what prompted a more explicit how-to view explaining the exit action in Android 5.1.
However this feature once again doesn’t take into account the Android soft keys. When a screen is pinned, why not change the graphics for Back and Overview to pin icons. This would also reinforce the fact that the phone is in a separate “pinned screen” mode.
As always, thoughts are welcome 🙂