bug#81441: [PATCH] Have 'toggle-rot13-mode' behave buffer locally

Eli Zaretskii <[email protected]> writes:

> Ping!  How should we make further progress in this matter?

I would suggest adding a new minor mode that changes the display table
of the buffer, and not the frame.

>> Cc: [email protected]
>> Date: Tue, 21 Jul 2026 14:01:20 +0300
>> From: Eli Zaretskii <[email protected]>
>> 
>> > From: Philip Kaludercic <[email protected]>
>> > Cc: [email protected]
>> > Date: Mon, 20 Jul 2026 19:10:29 +0000
>> > 
>> > Eli Zaretskii <[email protected]> writes:
>> > 
>> > >> From: Philip Kaludercic <[email protected]>
>> > >> Date: Sun, 19 Jul 2026 21:23:25 +0000
>> > >> 
>> > >> I was recently surprised that this command changes the display table of
>> > >> the window, which if confusing if you switch between buffers or move
>> > >> them around between windows.  I would suggest just changing the
>> > >> behavior outright, without a replacement as the function remains simple
>> > >> enough to write oneself if a per-window workflow is that important
>> > >> (which is doubtful considering that we are talking about rot13 here).
>> > >
>> > > This has a clear downside: using a buffer display table means you
>> > > cannot have this buffer shown in another window as human-readable
>> > > text.
>> > 
>> > Do you think/know that that is a common use-case?
>> 
>> I don't know for sure, but that's my strong impression both from the
>> documentation and from what the command does.
>> 
>> Also note that this is email-related feature, and it is unusual to
>> have the email reading buffer be displayed in more than a single
>> window.  At least when using Rmail, there's usually just one window
>> which shows the message.
>> 
>> > > So I don't think we should make such a change, except as an opt-in
>> > > behavior.  The documentation of this feature clearly hints that the
>> > > rot13 display is ephemeral, so IMO window-specific display table is a
>> > > better default.
>> > 
>> > I see your argument, but I don't think that either is strictly
>> > preferable.  Would it make sense to then instead add a proper buffer
>> > local minor mode `rot13-buffer-mode' as an alternative to existing
>> > command?
>> 
>> I don't see how it could be an alternative, because a mode by
>> definition affects the buffer in any window.  We could have such a
>> mode _in_addition_ to the existing command, though.
>> 
>> 
>> 
>>