Ubuntu 18.04 has purple border on the bottom, and right side of the screen, sometimes

Question

As I'm writing this on Firefox, the purple border is not there. Only Firefox does not show the border, as far as I'm aware.

This is what it looks like.

The cursor still appears in it, but the wallpaper doesn't cover it, and appears to be exactly 2 pixels wide.

I first noticed when I shifted 'focus' from a full screen game, to just the desktop using the super key.

I have a 1080Ti and I am using the proprietary Nvidia driver, 430.

16gb ram, Intel Xeon V2, 8gb swap.

Thanks.

Answer 1

I found the error, just turn off the zoom feature from Universal Access menu in settings. The purple border just disappeared.