Reconsider / improve tap-to-toggle-fullscreen

[ericwa]

One review on the play store found it annoying. They say they almost never use fullscreen.

I do find myself accidentally toggling fullscreen too, especially when trying to tap on links.

[ericwa]

According to the android developer guide here:
https://developer.android.com/design/patterns/fullscreen.html
we probably should be using the "Immersive" UI pattern instead of "Lean Back" (tap anywhere to toggle fullscreen).