Hiding the back/home button bar?

i’ve noticed on my Nvidia shield that the bar with the back/home button is automatically hidden when I load up a game in retroarch, however when I use retroarch on my Z3 compact the bar is always there. is this fixable on the Z3 compact or will I have to see the bar up at all times?

i’m using the stock retroarch from the play store. 1.0.0.2