Black rectangle appears on display

Question

Ever since I upgraded to macOS High Sierra, I’ve had a black rectangle on my screen:

My cursor started out inside it, and when I try to move my cursor outside of it, it follows my cursor:

I’ve tried restarting and quitting all of my other apps, it still shows up.

If I switch the “Zoom style” in System preferences → Accessibility → Zoom to “Picture-in-picture,” the box still shows up, but it stops following my cursor.

How can I get rid of this annoying box?

Answer 1

It turns out that this is actually a “feature.” There’s an option in System Preferences → Accessibility → Zoom → Options…:

Unchecking that should remove the rectangle.