seminar.cls has a bug that prevents proper working with the "a4paper" option. (Option "a4" works).
the seminar and prosper packages are still buggy.
The bug prevents use of seminar as doctype from LyX together with the geometry package and a4 option, as LyX inserts:
\usepackage{geometry} \geometry{verbose,a4paper,tmargin=1cm,bmargin=1cm,lmargin=2cm,rmargin=2cm}
and subsequentely, LaTeX reports an "! Undefined control sequence." error
I wonder, whether the prosper package built on seminar is affected too...
As seminar.cls is no longer maintained by the author, fixing it upstream is nontrivial. I filed a bug to the the Debian maintainer of tetex-extra Frank Küster and got a prompt response inclusive improved patch:
I do not think that this is the right way to create a special package for LyX. You also can insert these lines into the preamble without doing it from inside LyX.
\usepackage{geometry}
\geometry{verbose,a4,tmargin=1cm,bmargin=1cm,lmargin=2cm,rmargin=2cm}Herbert
