Grey semi circle won't go away !

[shibbikitteh]

How on earth do I get rid of this !
I thought it was multi tray or flip book but I've held back and disabled flip book.
If I rotate my screen it moves also, however i can't press it, it doesn't do anything if I swipe or tap it.

Does anyone have a clue ?

 

[B. Diddy]

Welcome to Android Central! Does it remain if you boot into Safe Mode? https://support.t-mobile.com/docs/DOC-27712