bug#35571: bug#35696: preview-latex does not work under any Emacs themes and bug#35571: 12.1; Changing foreground breaks previews

[Ikumi Keita]

[Adding address@hidden in To: field may result in too many
duplicated delivery of this message, so I refrain from doing so.]

Hi David and all,

>>>>> David Kastrup <address@hidden> writes:

> It never was a problem for myself since my windows are black on white.
> This code is for people who expect preview-latex to do something more
> useful than the default on other setups.

Thanks for confirmation.  I understand your point of view.

Then, I'd like to ask other developers what we should do.  Some options
which came to my mind, in no particular order, are:

(1) Make `preview-pdf-color-string' just a no-op and drop the feature
to match the foreground color of the generated image with the default
face of emacs.
(2) Find someone to revise the Postscript code in
`preview-pdf-color-string'.  Maybe we can ask the developer of
Ghostscript, looking at the paragraphs [1]:
"The process of "tidying" the Postscript name space should have removed
only non-standard and undocumented operators. Nevertheless, it is
possible that any integrations or utilities that rely on those
non-standard and undocumented operators may stop working, or may change
behaviour.
If you encounter such a case, please contact us (either the #ghostscript
IRC channel, or the gs-devel mailing list would be best), and we'll work
with you to either find an alternative solution."
(I'm not sure this is a good idea or not, since similar problems may
recur in future even if the current case is resolved.)
(3) Find and ask someone to develop elisp code along with the David's
suggestion of circumventing pdf2dsc.  (Though I have an impression that
it's difficult to find a person skillful enough to carry out such a
task, other than David himself.)

Of course the alternatives are not limited to the above three.

[1] https://www.ghostscript.com/doc/9.27/History9.htm

Regards,
Ikumi Keita