I erroneously assumed (and thought I tested) that using `tmm-prompt`
could be done the way I described before. The `oni:mailbox-map`
variable needs to be a little different from what I'd shown before,
namely:

[[!format el """
(defvar oni:mailbox-map
  '("top" ("menu" ("ryulash.org" . "ryu")
           ("ninthfloor" . "ninthfloor")
           ("gmail" . "gmail")
           ("aethon" . "aethon")))
  "A mailbox map for use with `tmm-prompt'.")
"""]]

Without the *top* and *menu* items it will complain about wrong
arguments.

[[!meta date="2012-05-02 21:52:00"]]
[[!meta title="Ask for selection in emacs, addendum"]]
[[!tag emacs elisp coding]]