bug#73175: 30.0.60; toggling emacs-news-view-mode doesn't remove buttons

[Robert Pluim <rpluim@gmail.com>]

>>>>> On Fri, 20 Sep 2024 09:52:25 +0300, Juri Linkov <juri@linkov.net> said:

    >> src/emacs -Q etc/NEWS
    >> C-x C-q ; buttons appear
    >> C-x C-q ; buttons donʼt disappear
    >> 
    >> (personally I donʼt mind the buttons, but the intent of faf1f037987c
    >> was to make them disappear).
    >> 
    >> I came up with the following, but I can never remember all the details
    >> of text property removal (maybe we need a `button-debuttonize-region'?)

    Juri> Or `button-unbuttonize-region' (like in `gnus-unbuttonized-mime-types').

Sure.

    >> (define-derived-mode emacs-news-mode text-mode "NEWS"
    >> "Major mode for editing the Emacs NEWS file."
    >> ;; Disable buttons.
    >> -  (button-mode nil)
    >> +  (button-mode -1)
    >> ;; And make the buffer writable.  This is used when toggling
    >> ;; emacs-news-mode.
    >> (setq buffer-read-only nil)
    >> +  (save-excursion
    >> +    (with-silent-modifications
    >> +      (widen)
    >> +      (remove-text-properties (point-min) (point-max)
    >> +                            (button--properties nil nil nil))
    >> +      (add-face-text-property (point-min) (point-max)
    >> +                              'button nil)))

    Juri> Probably it would be the right thing to move this code to `button-mode'
    Juri> to remove properties when it's disabled.

That would be best (assuming Iʼve got the incantation right ;-))

Robert
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