Internationalization: set default language

[Rod Widdowson]

> It was my impression that the "fallback language" isn't "what to use if a message doesn't exist in a given language" but "which
> language to use if no language is set/derived", 

That's correct.

> and I'm not sure that even affects messages (I don't recall, I was thinking it was just for
> metadata UI extension content, that sort of stuff).

Now you mention it, I'd agree with that too...

R