Is there a way to do an automatic list-choices after successful completion of directory name?

["Nikolai Weibull" <now@bitwi.se>]

I would like list-choices to be run whenever I have completed a
directory name, e.g.,

  $ cd ~/p<Tab>

completes to

  $ cd ~/projects/

Once completed, I'd like list-choices to be called so that I can see
what directories I have under ~/projects immediately, instead of
having to type another <Tab> right after the first one.

I assume I'll have to write my own completer that I'll bind <Tab> to
that first does a call to _complete somehow, but how do I then tell if
a directory name is what has been completed?

Thanks.

  nikolai