General ⇒ Examples in LaTeX Companion

[NinV]

OK, I succeeded to 'correct' it! Now it works fine for me.

Code: Select all

\documentclass[10pt,a4paper,twoside]{book}
\usepackage[thref]{ntheorem}
\usepackage{ifthen}

\makeatletter
\newcounter{pl}
\renewtheoremstyle{marginbreak}%
  {\stepcounter{pl}\label{pl-\thepl}%
    \ifthenelse{\isodd{\pageref{pl-\thepl}}}
     {
      \item[\rlap{\vbox{\hbox{\theorem@headerfont
            \llap{\fbox{##1 ##2}}\hskip\labelsep\relax
            \theorem@separator}\hbox{\strut}}}]}
     {
      \item[\hskip1.7cm\rlap{\vbox{\hbox{\theorem@headerfont
            \rlap{\hspace{1.1\textwidth}\fbox{##1 ##2}}\hskip\labelsep\relax
            \theorem@separator}\hbox{\strut}}}]\hskip-1.7cm}
  }
  {\stepcounter{pl}\label{pl-\thepl}%
    \ifthenelse{\isodd{\pageref{pl-\thepl}}}
         {\item[\rlap{\vbox{\hbox{\theorem@headerfont
           \llap{\fbox{##1 ##2}}\hskip\labelsep\relax\
           ##3\theorem@separator}\hbox{\strut}}}]
         }
         {\item[\hskip1.7cm\llap{\vbox{\hbox{\theorem@headerfont
           \rlap{\hspace{1.1\textwidth}\fbox{##1 ##2}}\hskip\labelsep\relax\
           ##3\theorem@separator}\hbox{\strut}}}]\hskip-1.7cm%
         }
  }
\makeatother

\theoremstyle{marginbreak}
  \theoremheaderfont{\normalfont\bfseries}\theorembodyfont{\slshape}
  \theoremsymbol{\ensuremath{\clubsuit}}
  \theoremseparator{:}
  \newtheorem{reg}{Ex.}

\begin{document}

text text text text text text text text text text text text text text text text text text text text text text text
text text text text text text text text text text text text text text text text
\begin{reg}[Test 01]\label{t01}
  Test example one
\end{reg}

\newpage

text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text
\begin{reg}[Test 02]\label{t02}
  Test example two
\end{reg}

\end{document}

Thank you very much for your help!