bug#38645: 26.3; minibuffer input is called with multi-line window when multi-line message is shown

[Eli Zaretskii <eliz@gnu.org>]

> Cc: ynyaaa@gmail.com, 38645@debbugs.gnu.org
> From: martin rudalics <rudalics@gmx.at>
> Date: Sun, 29 Dec 2019 20:30:47 +0100
> 
>  >> Did you check whether any of the
>  >> other clear_message calls would need a similar treatment?
>  >
>  > Which ones?
> 
> Maybe the last one in read_char itself.  But I don't understand well what
> we are doing there.

We are evidently clearing the echo area if the input method left
something there.  But I couldn't create a situation where there was
anything left to do after the input method finished its job, not by
turning on an input method in the active minibuffer.  Quail has its
own ideas about handling this situation; see quail-minibuffer-message
and quail-show-guidance.  In particular, it arranges for the guidance
to appear on the second line of the mini-window (the first one being
where you type at the prompt), and never shows more than one line of
candidates for input there (you need to scroll with up- and
down-arrows).  And when input is done, the mini-window resizes back.

So if someone knows how to trigger a mini-window resizing problems
related to input methods, please show a recipe (and reopen the bug).

Meanwhile, I've installed the fix and I'm closing this bug report.

Thanks for the feedback.