I don't want to be difficult, or anything, Luigi. But I acrually looked this up to be sure I was spelling "dialogue" correctly. Most people accept Merriam-Webster as the authoritative American dictionary, and the OED as the leading British authority.

MW: dialogue noun di·​a·​logue | \ ˈdī-ə-ˌlȯg, -ˌläg \ variants: or less commonly dialog OED: dialogue noun /ˈdaɪəlɒɡ/ /ˈdaɪəlɔːɡ/ (US English also dialog)

https://www.merriam-webster.com/dictionary/dialogue https://www.oxfordlearnersdictionaries.com/definition/english/dialogue

So the preferred spelling is "dialogue" in both the UK and the USA. "dialog" is recognized as correct, but is less commonly used. I personally don't much care which way it's spelled. Either way shuld be OK.

@davidbryant please use "dialog"

The documentation is referring to special type of pop-up window called a "dialog". .. you know computer terminology brought to you by the same type of people who invented such OED words as "emoticon" :) It is not referring to a discussion between human beings ("dialogue")

Thank you for the explanation, Alan. As I told Luigi, it's no big deal.

So far, at least, neither Webster's nor the Oxford crowd has seen fit to bless the neologism "dialog" with its own entry in the lexicon. I do see it cited separately in such paragons of erudition as "The Free Dictionary". But even those guys say it's just a variant of dialogue.

Not that it matters, but isn't a dialog with a computer a form of dialogue between two human beings? The user, and the programmer. Yes, they're separated by time and space -- even farther apart than you and I are, perhaps. But the speaker and the listener are always separated by time and space, at least a little bit. d = √x² + y² + z² - c²∙t².

David Bryant Canyon Lake, Texas

https://www.merriam-webster.com/dictionary/dialog%20box

In this case, also, consistency matters: we do use it everywhere.