The System UI Tuner was only introduced in Marshmallow, but it's already got quite a few features, with one graduating to a fully-fledged feature (and others causing quite a bit of controversy). The next thing Google seems to be working on for it is a navigation bar customizer, allowing quite extreme customization of the now standard back-home-recents navbar.

The navbar customizer is currently hidden in Nougat's code.

Read More