It would be a nice feature to be able to control volume directly on the navbar.
Tap and hold on any position of the navbar - move right to increase or left to decrease volume.
(just like the normal volume slider of android but in horizontal direction)
This would avoid to search the volume +- button or a second click on the original volume slider, so more userfriendly.
I know there are gestures possible with two or three finders but i think it would be better to do this on the navbar, so you can avoid any mistakes with apps and movement of content of apps like with the gestures.
Maybe an idea for future release.