%% 
%%  The LaTeX Graphics Companion, 2ed (first printing May 2007)
%% 
%%  Example 6-2-28 on page 346.
%% 
%%  Copyright (C) 2007 Michel Goossens, Frank Mittelbach, Denis Roegel, Sebastian Rahtz, Herbert Vo\ss 
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 

\documentclass{ttctexa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{159.83385pt}
\StartShownPreambleCommands
\usepackage{pstricks,pst-node}
\StopShownPreambleCommands
\begin{document}
\begin{pspicture}(3,3)  \large
  \psset{nodesep=3pt,linearc=0.3}
  \rput[bl](0,0){\rnode{A}{1}}
  \rput[tr](3,3){\rnode{B}{2}}
  \ncbox{A}{B}
  \rput[lt](0,3){\rnode{A}{3}}
  \rput[rb](3,0){\rnode{B}{4}}
  \ncbox*[border=4pt,linecolor=lightgray]{->}{A}{B}
  \rput[lt](0,3){\rnode{A}{\textbf{3}}}
  \rput[rb](3,0){\rnode{B}{\textbf{4}}}
\end{pspicture}
\end{document}