[AUCTeX] preview-latex with preamble in input file

[Erik Granstedt]

Hello,

I recently started using AUCTeX to write LaTeX documents inside Emacs,
and I'm hooked.  The preview-latex package is a quite helpful
component, in particular, the ability to run latex on individual
equations in my document.  I have run into an issue, however, when I
use \input{file} statements at the beginning and end of the document.
I find it convenient to put preamble and epilogue(?) information in
these separate files, so that I can focus on the particular document
that I'm writing.  This also makes it easy to process the document for
different standard formats.

The preview package works fine as long as I only generate previews for
the entire document.  If I try to regenerate a particular environment
or section, I receive a latex error:

(./_region_.tex  !name(test.tex)  !name(test.tex) !offset(6)

! LaTeX Error: Missing \begin{document}.

I have tried both caching and not caching the preamble, with the same
result. If I then remove all the previews from the document and
regenerate all the previews, it works again.  Is there a way to get
the preview-latex package to work fully using the preamble in an input
file?

Thanks,

-Erik