desktop arrow appears wheh pressing any Nav-Key

[downup]

Try it, hold down
Arrow, home button or the search button on your 1520. And a windows desktop arrow will appear in the left top corner.

:O

Any idea why? Works on any screen/app

 

[Harrie-S]

Yes this is the mouse pointer. If you connect a Bluetooth mouse then you can move this pointer.
Everyone on W10 sees it and it is probably a bug that we see it.
If you do not want to see it you could connect a bluetooth mouse and "drag" the mouse out of the "visible" area.