bug#74833: 31.0.50; Copy to OS clipboard doesn't work in macOS Terminal.app with xterm-mouse-mode enabled

[Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

> +(defconst xterm--auto-xt-mouse-allowed-names
> +  (mapconcat (lambda (s) (concat "^" s "\\>"))
> +             '("Konsole"
> +               "WezTerm"
> +               ;; "XTerm"   ;Disabled because OSC52 support is opt-in only.
> +               "iTerm2"     ;OSC52 support has opt-in/out UI on first usage
> +               "kitty")
> +             "\\|")

Sounds good, tho I'd use

    (concat "\\`" (regexp-opt '(...)) "\\>")

> +(defconst xterm--auto-xt-mouse-allowed-types
> +  (mapconcat (lambda (s) (concat "^" s "$"))
> +             '("alacritty"
> +               "contour")
> +             "\\|")

Same here (with \` and \')

> +  "Like `xterm--auto-xt-mouse-allowed-names', but for the terminal's type.
> +This will get matched against the environment variable \"TERM\".")

We should clarify if it's an "and" or an "or": if only one of
the two vars matches, is the feature enabled or not?

> @@ -907,7 +963,15 @@ xterm--init
>  
>    (when xterm-set-window-title
>      (xterm--init-frame-title))
> -  (when xterm-mouse-mode
> +  (when (and (not xterm-mouse-mode-called)
> +             ;; Only automatically enable xterm mouse on terminals
> +             ;; confirmed to still support all critical editing
> +             ;; workflows (bug#74833).
> +             (or (string-match-p xterm--auto-xt-mouse-allowed-types
> +                                 (tty-type (selected-frame)))
> +                 (and-let* ((name-and-version (xterm--query-name-and-version)))
> +                   (string-match-p xterm--auto-xt-mouse-allowed-names
> +                                   name-and-version))))
>      (xterm-mouse-mode 1))
>    ;; Unconditionally enable bracketed paste mode: terminals that don't
>    ;; support it just ignore the sequence.

- The above enables `xterm-mouse-mode` which will
  then proceed to *not* obey `xterm--auto-xt-mouse-allowed-*` on any
  further ttys used in the same session.

  IOW, I think the above test belongs in
  `turn-on-xterm-mouse-tracking-on-terminal` rather than here.

- Maybe instead of `xterm-mouse-mode-called` we should test

    (eq xterm-mouse-mode 'when-safe)

  or maybe rename the var to something more explicit like
  `xterm-mouse-mode-only-when-safe`.

- Of course, the previous code was also very weird:

    (when xterm-mouse-mode (xterm-mouse-mode 1))

  says to enable the mode, but only when it's already enabled?!


        Stefan