Richard,

> I rather like having messages in separate files because

I don't mind having them in separate files ... what I *do* mind is having
them in external files exclusively and no relation to the context they're
used in.

> + You can give them to someone to translate who doesn't have to know
>   about the programming language involved.

True and not true. As I said, the loss of context is a big issue here. It
makes it extremely hard for that person to get an answer to the question "in
what context are you using this phrase?!" which was effectively the only
question we ever got from people translating stuff for us.

> + A program can dynamically switch languages (quite handy when a
>   lecturer's preferred language isn't the same as a student's
>   preferred language).

That doesn't appear to be directly related to separate files, does it?!

> + Variant: the same image can provide messages in English
> when run by me
>   or Maori, Chinese, whatever when run by a student who'd prefer that.
>   (Yeah, dream on...)  The student wouldn't have to start a
>   different image or load a special change-set.

What do you mean "dream on"?! Do you realize that what you're describing is
already practice in the eToy system?! All you have to do is to toggle the
current language - so if anything we most certainly must be able to do
exactly that.

> + Messages only have to be edited in one place however many
> places they are used.

That's really only a question of the tools you provide... 'know what?! I'll
see if I can find a few hours on the weekend to make a rough mockup of what
I'm talking about. Perhaps that'll make a few points clearer.

Cheers,
  - Andreas