I've never seen the words "dialogue box". If I'm speaking of drama, that's dialogue; but but an interactive box in a computer UI is a "dialog".

In the same way, the instructions controlling a computer are a "program"; the TV drama with the dialogue is a "programme".

/me British English speaker (obv)

Check out GIMP - its window menu includes an entry for "Dockable Dialogues", at least on macOS. Might be close enough? I don't think I've ever seen anybody else spell it that way though!

(This would also, if you squint a bit, serve as an example of "dialog" being short for dialog box.)

I am in the uk and have never heard "dialog" used by British speakers any other way. My experience has near universally that everybody that knows the term spells it "dialog", same as nobody spells "disk" with a c when it comes to the rectangular computer variety.