How do I disable/remove this box around the currently focused item in OSX?

Question

Notice the black box around the content area. It should look like the following:

I'm not sure what I pressed to get this, but it just started showing up and I'm not sure what's causing it. It shows up in every application.

Any ideas on how to disable it or what might be causing it?

Answer 1

Ah! Found the answer: http://forums.macosxhints.com/showthread.php?t=41256

It's to do with voice over, which I guess is triggered on my machine by pressing ⌘F5