bug#81667: 32.0.50; `query-replace-show-preview' includes Quail IME UI and suggestions in buffer preview

> From: Rahul Martim Juliato <[email protected]>
> Cc: [email protected],  [email protected], [email protected],
>  [email protected]
> Date: Fri, 21 Aug 2026 00:38:59 -0300
> 
> diff --git a/lisp/international/quail.el b/lisp/international/quail.el
> index 39c10287f3c..f838bc9ab8e 100644
> --- a/lisp/international/quail.el
> +++ b/lisp/international/quail.el
> @@ -1998,14 +1998,22 @@ quail-require-guidance-buf
>  
>  (defun quail-minibuffer-message (string)
>    (message nil)
> -  (let ((point-max (point-max))
> -	(inhibit-quit t)
> -        (deactivate-mark nil))
> -    (save-excursion
> -      (goto-char point-max)
> -      (insert string))
> -    (sit-for 1000000)
> -    (delete-region point-max (point-max))
> +  (let ((inhibit-quit t)
> +        ;; Display the guidance with an overlay instead of inserting it
> +        ;; into the minibuffer, so that it stays out of the minibuffer
> +        ;; contents (bug#81667).
> +        (ov (make-overlay (point-max) (point-max) nil t t)))
> +    (unwind-protect
> +        (progn
> +          ;; Tell the display engine to keep the cursor before the
> +          ;; guidance, where point is.
> +          (unless (zerop (length string))
> +            (setq string (copy-sequence string))
> +            (put-text-property 0 1 'cursor t string))
> +          (overlay-put ov 'after-string string)
> +          (overlay-put ov 'priority 1100)
> +          (sit-for 1000000))
> +      (delete-overlay ov))

Please don't replace the old method of showing guidance with this new
method which uses an overlay.  The effect of such a change is too
dramatic for it to be made globally, for all the uses of Quail, so
doing that for the benefit of a relatively niche feature such as
query-replace-show-preview is not a good idea.

Instead, please make the new method be used when some new variable is
bound non-nil, and then bind that variable in
query-replace-show-preview.  This way, only this new feature is
affected, and we get enough time to learn how well this solution works
before thinking whether to make it the default.

Thanks.