[bug] latex fragment preview with dvipng ignores :foreground specification

[Eric S Fraga <e.fraga@ucl.ac.uk>]

Hello,

I am trying to use org-tree-slide for an interactive session I have to
facilitate soon.  This works quite well, in a geeky kind of way ;-)

However, I do want to display a couple of equations and using latex
fragments is the most appealing mechanism.  When I try to use
org-preview-latex-fragment, the latex image is
generated.  Unfortunately, as I use a black background on my display, I
cannot see the fragment as it is being generated with black text on a
transparent background by default.  Note, I am using dvipng for the
image conversion.

I can customise org-format-latex-options to fix this, or so I
thought.  No matter what I do, the resulting latex fragment has black
text.  The problem appears to be that the -fg option to dvipng does not
work so it doesn't matter how I customise org-format-latex-options.

Can anybody suggest a workaround (without changing the actual latex
itself)?  I can customise the above variable to set the background for
latex images to white, which at least allows the equations to be seen,
but this is a mildly ugly solution.  :( And ruins any geek street cred I
might have had ;-)

Thanks,
eric

-- 
: Eric S Fraga, GnuPG: 0xC89193D8FFFCF67D
: in Emacs 24.3.50.1 and Org release_7.9.3d-874-gf11acc