Sorry I should have said that I did that a few time. Moved it to alt+F and a few other combinations. They all have the same effect. Mouse does deactivates.
Also under the WMR the app starts as a desktop screen. It never fully imerces, so moving my head does move the mouse or player but also moves out of the frame. Mostly like watching a big screen, that WMR already has.
I am guessing it should start and be black screen all around. Am I correct?