I am a newbie to UltraEdit 11.00a, although I have used earlier versions.

When typing, an annoying box is appearing immediately to the bottom right of the typed character. As I continue to type, it moves to keep this position with each character entered.

Since I don't know what this box is called, or supposed to do, and clicking in it doesn't seen to achieve anything useful, I am having problems trying to identify what it is, and how to disable it.

Can anyone please offer some insight here?

You are quite correct, thanks for such a prompt response!

Initially the auto-complete option was not set, so I set it. Predictive words now began to appear in the box. When I then disabled the option, both the text - and the box - have now disappeared.

Is this a known minor bug?

This is how it's supposed to work. Ctrl+Space will bring up the box on demand.