Org LaTeX Beamer export and the order of loading packages and theme (XeLaTeX and fonts)

[Lennart C. Karssen]

Dear list,

I have been happily using the LaTeX Beamer export for several years. 
Recently, I had to update one of the themes I use for the slides and ran 
into a problem related to the order in which the theme and the LaTeX 
packages are exported to the .tex file.

I use XeLaTeX to compile my documents so I can use fonts like Fira Sans 
in my slides. For this, I load the fontspec package in my Beamer theme 
font file. The Org export code puts the #+BEAMER_THEME options after the 
packages loaded org-latex-packages-alist (and those specified on 
#+LATEX_HEADER lines) in the LaTeX preamble. In my case this gives a 
font problem, because my org-latex-packages-alist loads the polyglossia 
package (which loads the fontspec package needed for the fonts), but my 
beamer theme also tries to load fontspec and somehow (probably related 
to options passed to fontspec), this leads to different (unwanted) 
behaviour.

The desired behaviour would be to have sans-serif math in my equations, 
which works fine if I load my theme before loading other packages (in 
pure LaTeX). However, in the case of Org export, the \usetheme{} 
commands ends up after the \usepackage lines, which leads to serif fonts 
in my equations.

So my questions are basically the following:

1) Is there a way to tell Org to export the #+BEAMER_THEME lines before 
anything else?

2) Is there a reason why the Beamer theme options are exported after 
other LaTeX packages? Wouldn't it be better to export the Beamer theme 
options before loading additional packages? The reason for that being 
that the theme sets defaults, which can then (potentially) be altered by 
loading additional packages.


Best regards,

Lennart Karssen.
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L.C. Karssen
's-Hertogenbosch
The Netherlands

lennart@karssen.org
GPG key ID: A88F554A
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