03-31-2014, 03:46 PM
The soft ones don't completely disappear - they are just dimmed. You can always tap on the dim area at the bottom and all three buttons will appear again. If you are using a Nexus 10 running Android 4.4 (KitKat), then you have the option for a true full screen mode. If you enable this, you can access the navigation buttons by swiping up on the bottom of the screen.
Mike
Mike