Hi Arash, OK, thanks for your response, please feel free to close. Thanks, best,  Paul 

On Sat, 4 May 2024 at 15:59, Arash Esbati <arash@gnu.org> wrote:
Hi Paul,

Paul Nelson <ultrono@gmail.com> writes:

> This patch has no effect on existing behavior (in LaTeX-mode), but
> makes it so that preview-region works in any non-LaTeX-mode buffer for
> which TeX-master has been set to a valid tex file.  This is intended
> for internal use by other packages.  For example, I've been using
> something equivalent to this to preview org-mode LaTeX source blocks,
> tex code in Lean4 comments, (...).
>
> (One could avoid this patch by manually initializing TeX-header-end
> and TeX-trailer-start before calling preview-region, but it seems
> better to me to provide working defaults as in the patch.  Any
> feedback would be welcome, of course.)

I'm a little reluctant about this change; tex.el provides generic
functions/variables which are set by the modes; `TeX-header-end' and
`TeX-trailer-start' are some of them.  My preference is what you
describe above: If `preview-region' is used outside `LaTeX-mode', the 2
variables should be initialized there somehow and not inside tex.el.

Best, Arash