bug#11939: 24.1; `save-buffers-kill-emacs' loses minibuffer focus whenit calls `list-processes'

[Drew Adams]

>  > After the command I am at top level.  And I am in no way 
>  > stuck in a minibuffer window.
>  >
>  > The problem is that the `current-buffer' is " 
>  > *Minibuf-0*".  That's all.
> 
> So you mean you are at top level, the selected window is the 
> minibuffer window, its buffer is current, and you've never
> seen such behavior.  Is that a correct description of what you
> experience?

I think we're both probably getting a bit lost in all of the emails, especially
with the lapse of time, different tries of different scenarios, and encountered
side issues (e.g. crashes).  I apologize for contributing to that.

Here's the (current) issue and scenario.  It uses my setup (with untweaked
oneonone.el but also with the other libraries that I use).  The only thing I've
done differently than usual is to evaluate this sexp:

(add-hook 'after-make-frame-functions
          (lambda (frame)
            (redirect-frame-focus frame
             (window-frame (minibuffer-window)))))

I do M-x shell.
Then I do C-x C-c.

The `yes-or-no-p' prompt about active processes appears in the minibuffer.  I
type "no" into the minibuffer.

So far so good.  Things are perfectly normal now, and I am at top level (the
minibuffer has exited normally).

I then do C-x k.

Because my setup automatically inserts the default value (what `M-n' gives),
that buffer-name value is inserted in the minibuffer, waiting for me to hit RET
to accept it or to edit it and then hit RET.

The default buffer name in this case is " *Minibuf-0*".  That is what I have
never seen before.  I.e., without adding that `add-hook' sexp (above), I do not
get this behavior.

But I am not in any way trapped in the minibuffer.  I can edit the buffer name
to kill the buffer I want.  Or I can hit C-g.  And so on.

The only problem is that the value of `(current-buffer)' is " *Minibuf-0*" at
that point.  I know that by testing with `message' etc.  That is why I
hypothesized that something in that frame focus redirection caused the buffer "
*Minibuf-0*" to become selected, i.e., the `current-buffer'.

But you corrected me, pointing out that `yes-or-no-p' does that: it selects the
minibuffer window/buffer.

If I do not do the `add-hook', then I cannot type yes/no to the `yes-or-no-p'
prompt, without first manually selecting the minibuffer frame (e.g. by clicking
its titlebar).  And if I do that then the symptoms are the same as when I use
the `add-hook': after typing "no", if I use C-x k then " *Minibuf-0*" is the
default buffer to kill.

But if (I do not do the `add-hook' and) I do `M-: (yes-or-no-p "Foo? ")' and I
answer "no", then `C-x k' uses another buffer (the one selected before the M-:)
as the default value.  I am not sure why this difference, i.e., why
`yes-or-no-p' does not leave " *Minibuf-0*" as the current buffer in this case.
But it probably has to do with the execution of command `M-:' - IOW, in that
test it is not just `yes-or-no-p' that is involved, but also `M-:'.

So perhaps this is only a problem with (because of) `yes-or-no-p'.  And perhaps
there is nothing that can (or should?) be done about it.  It is anyway a minor
problem compared to the general problem that this bug report is about: loss of
focus to the minibuffer frame.

I hope we are now clear about this `C-x k' default-buffer problem.  Dunno what
can or should be done about it.  It seems (to me, so far) to be a problem with
`yes-or-no-p' (and perhaps some other functions?):

In order to ask its question, `yes-or-no-p' not only redirects input focus to
the minibuffer but it also (apparently) selects the minibuffer's buffer.  And it
apparently leaves that buffer selected, as the `current-buffer'.

You know better than I what, if anything could/should be done to correct this.
Should `yes-or-no-p' use `with-current-buffer' or something, so that it finishes
by selecting again the buffer that was selected when it started?  I'm guessing
yes, but I know nothing about the code.  It seems wrong that it should change
the selected buffer to the minibuffer and leave it so changed.

The above behavior description holds for all Emacs versions I have.  The
`add-hook' solves the unfocused minibuffer frame problem for all versions.

That means also that for Emacs 24 I do not need to use the
`with-temp-buffer-window.el' code you sent.  It is sufficient to use the
`add-hook'.  Dunno whether that helps you decide something for Emacs 24.

Given the info above, do you think that the equivalent of that `add-hook' should
perhaps be built into Emacs?  IOW, is some code correction in order, to do
systematically what the `add-hook' workaround accomplishes?