Sorry for committing to send an updating patch but not replying for so
long...

Good that the broken patch was quickly fixed after it broke colors in
the macOS Terminal app. I looked again into the issue. One potential
further pitfall is that the Tc logic in tmux, which introduced the Tc
flag, is still different from what we do: while Tc is meant to mean
"support for the default sequences as in xterm+direct", tmux first
relies on the setrgbf/setrgbb escape sequences in the terminfo and only
provide the default sequences if setrgbf/setrgbb are not present.
 
I've attached a patch that would introduce full support for
setrgbf/setrgbb as previously proposed [2]. Before I propose an update
for the efaq.texi, let me know if you're interested in this patch (with
a proper commit messagea and NEWS entry) or not.

I personally don't care too much. With the Tc fix applied, Emacs works
for me, and believe our current code is fine, even though we don't
fully replicate tmux's logic respect to Tc. On the other hand, with
full support for setrgbf/setrgbb, we'd support pretty much every
existing method out there and the diff is not that large.

Best,
Tim



[1] See for example
https://github.com/tmux/tmux/commit/7eb496c00c313c2f8ab8debe6d154d5ac0db277b#diff-de4f90e163caf6cc83476898c795355523776a76f9ccc7783e9bd3a99fde671dR526
(this code was replaced later in 
https://github.com/tmux/tmux/commit/a6129e99749d2bbc8b4a991c7b5d09300aa55f39#
but the logic is still the same and the earlier commit is easier to
read). Another relevant discussion is
https://github.com/tmux/tmux/issues/2418 .

[2] https://lists.gnu.org/archive/html/bug-ncurses/2013-10/msg00007.html



On Thu, 2021-11-11 at 07:15 +0100, Lars Ingebrigtsen wrote:
> Tim Ruffing <crypto@timruffing.de> writes:
> 
> > Hi Lars, not yet. I'm currently on vacation, I'll come back to you in
> > about two weeks.
> 
> This was some months ago, so I went ahead and pushed the change to
> Emacs
> 29.
>