Seminar: \end{slide} doesn't end \overlay's scope and gives postscript error

[frank@kuesterei.ch (Frank Küster)]

Dear seminar developers,

The following small document, when processed with LaTeX and dvips, gives
postscript file which has errors:

************************************
Error: /undefined in BOL
Operand stack:
   (all)
Execution stack:
   %interp_exit   .runexec2   --nostringval--   --nostringval--   --nostringval--   2   %stopped_push   --nostringval--   --nostringval--   --nostringval--   false   1   %stopped_push   1   3   %oparray_pop   1   3   %oparray_pop   1   3   %oparray_pop   1   3   %oparray_pop   .runexec2   --nostringval--   --nostringval--   --nostringval--   2   %stopped_push   --nostringval--   --nostringval--   --nostringval--
Dictionary stack:
   --dict:1061/1123(ro)(G)--   --dict:0/20(G)--   --dict:73/200(L)--   --dict:118/300(L)--   --dict:75/200(L)--
Current allocation mode is local
GNU Ghostscript 7.07: Unrecoverable error, exit code 1
************************************

The error occurs on the _third_ page, i.e. outside the slide
environment. It seems that \end{slide} doesn't properly close \overlay's
scope, since after removing the commented additional braces, the error
goes away.

It might not be an error in fact, but it should at least be documented,
I think. I have tested it with the files included in the latest
teTeX-beta. 

When answering, please be so kind and keep the bug number in the Cc, so
that the mails get properly archived.

Thank you in advance, Frank

\documentclass[semlayer,semcolor] {seminar}
\input{seminar.bug}
\input{seminar.bg2}

\title{Crashing Tutorial}

\begin{document}

\begin{slide}
What is Crashing?
\begin{itemize}
\item Crashing who you are to somebody else. 
\end{itemize}

%{
\overlay{1}
Why is crashing important?
%}
\end{slide}

Crashing is \textit{not} the same as collisions. Here are some
examples why this is the case:

\end{document}

-- 
Frank Küster, Biozentrum der Univ. Basel
Abt. Biophysikalische Chemie