a mathtext bug?

Hi, I am trying to use mathtex expression for Molecule

    > descriptions(in the legend)

Hi Malte, Thanks for the report -- I didn't know that $^12 something$
was legal TeX.

Try the attached mathtext.py, which I believe handles correctly all
three cases you posted.

Let me know....
JDH

mathtext.py (34.5 KB)