[pstricks] psgrid and psgraph

[Denis Bitouzé]

Hello,

in the following MCE, why the grid doesn't fill the (trimmed) psgraph
area?

\documentclass{article}
\usepackage{pst-plot}
\begin{document}
\psset{llx=-5cm,lly=-1cm}
\begin{psgraph}(0,0)(3.0,9.0){4cm}{5cm}
  \psgrid
\end{psgraph}
\end{document}

Thanks.
-- 
Denis