KDE (4.3) auto completion

This appeared in earlier versions of KDE (4.0+?) - and it’s driving me nuts. I’m not sure what it’s called, so couldn’t google it…

When using any app. in KDE, a little blue box appears under what I’m typing - with the text in it.

Without knowing what is is - and therefore what it can do - it isn’t helping me, so I’d like to disable it! anyone know how?

Or, perhaps better still, what is it, and how can I use it better?!

Thanks for reading,

Simon R