Code review comment for lp:~vanvugt/mir/wait-result

Well, I don't need this right now.

But in the near future when you can't tell if client functions succeeded or not, we'll need something. Preferably not callbacks, because they're so awkward to use. Maybe events, but still they're much more awkward for simple clients to use than what's presented here.

I really like this approach. In theory it allows us to completely abolish callbacks in future as you could do something like:

   wait = mir_create_surface();
   ...
   ... other things ...
   ...
   surf = mir_wait_for_a_surface(wait);