[pstricks] Corners of \pstThreeDBox look ugly

[Christoph Bersch]

Hi,

when using thicker linewidths, the corners of \pstThreeDBox look ugly. 
Consider the following example:

\documentclass{article}
\usepackage{pst-3dplot}
\begin{document}
\begin{pspicture}[showgrid=true](-2,0)(4,2)
\psset{Alpha=80,Beta=5,linewidth=0.1cm}
\pstThreeDBox[fillcolor=white,fillstyle=solid](-15,-1.5,0)(15,0,0)(0,3,0)(0,0,0.3)
\end{pspicture}
\end{document}

Version of pst-3dplot is v1.77, 2007/10/03

Is there any way to fix this?

Thank you
Christoph