Beta 2.99950: – When map is locked (with the touch screen lock settings enabled) other UI elements are hidden too
The idea is good. But, right now you remove bottom UI elements (menu) and show the same map area in increased screen space, which results in different aspect ratio. This is unpleasant, since eye catches this change (to prove my point: locking button is also a little bit distorted after reshaping of the map, not perfect circle anymore).
In my opinion, aspect ratio of the map and zoom level should stay the same after locking, so you just show increased “map area” (a little bit), that fit to screen.