@lakotaubp Stable @AppLee I know, but if nothing other works ... @all As nothing worked I reinstalled UBPorts. Now the file mananger seems to be fine.

@all Think the problem seems to be solved - in one or the other way ... As I wrote the red buttons are not functional - but only if the OnePlus is in portrait format. When it is in landscape the red buttons are functional ... If I draw lines in a graphical app there are blank parts on the screen, too. It seems I've got a problem with the hardware.