[denton-scratch]

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)

[tom_]

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.)