Re: Suggestions for the temporary windows used from the minibuffer

[Richard M. Stallman]

    If, instead of creating new commands, the existing command definitions were
    simply changed to effect an alternative behavior (~ a hook) when there is no
    "other" window, then that would simplify the implementation, at least.

Such a hook is not worth adding.  A specific useful fallback behavior
might be worth adding.

But please let's wait until after the release to discuss this.