bug#61022: 28.2.50; Mouse tracking of high coordinates not working in rxvt-unicode

[Eli Zaretskii <eliz@gnu.org>]

> From: git@vladimir.panteleev.md
> Date: Sun, 22 Jan 2023 19:36:50 +0000
> 
> For some reason, xt-mouse with xterm-mouse-utf-8 on isn't working for me
> under rxvt-unicode. I assume it worked at some point, but it's not
> working now.
> 
> I investigated it a little and it looks like the (read-char nil nil 0.1)
> call is no longer reading an entire UTF-8 character unless the
> inherit-input-method argument is non-nil. I don't know why that is.
> But, in any case, this patch fixes it for me:
> 
> ----------------------------------------------------------------------
> >From 32e4b5ab67006ed08c853396686315ed373691be Mon Sep 17 00:00:00 2001
> From: Vladimir Panteleev <git@cy.md>
> Date: Sun, 22 Jan 2023 18:54:05 +0000
> Subject: [PATCH] Fix xterm mouse tracking of high coordinates with
>  xterm-mouse-utf-8
> 
> read-char now needs inherit-input-method to be non-nil for it to read
> a whole UTF-8 code point, even with set-keyboard-coding-system.
> 
> * lisp/xt-mouse.el (xterm-mouse--read-coordinate): Call read-char with
> inherit-input-method as t.
> ---
>  lisp/xt-mouse.el | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lisp/xt-mouse.el b/lisp/xt-mouse.el
> index adfa480bc0f..2b6b448305e 100644
> --- a/lisp/xt-mouse.el
> +++ b/lisp/xt-mouse.el
> @@ -160,7 +160,7 @@ xterm-mouse--read-coordinate
>               'no-conversion))
>            ;; Wait only a little; we assume that the entire escape sequence
>            ;; has already been sent when this function is called.
> -          (read-char nil nil 0.1))
> +          (read-char nil t 0.1))
>        (set-keyboard-coding-system previous-keyboard-coding-system))))
>  
>  ;; In default mode, each numeric parameter of XTerm's mouse report is
> -- 
> 2.38.1
> ----------------------------------------------------------------------
> 
> Reproducer:
> 
> - Run urxvt
> - In it, run emacs -Q -nw
> - M-: (require 'xt-mouse)
> - M-: (setq xterm-mouse-utf-8 t)
> - M-x xterm-mouse-mode
> - Make sure the window is wider than 96 lines or columns
> - Move the mouse around past the 96th line or column
> 
> Hope this helps.

Jared, any comments?

Thanks.