[pstricks] pst-abspos and beamer not (quite) working

[Christian Häger]

Hello,

My intent is to be able to place PSTricks objects at arbitrary positions in my beamer presentation, having the upper left corner as a fixed reference point. However, it does not quite work. Here is my minimal example:

\documentclass[t]{beamer}
\usepackage{pstricks}
\usepackage[absolute]{pst-abspos}
\begin{document}
\begin{frame}{Testframe}%
\pstSetAbsoluteOrigin%
\pstPutAbs(0,0){%
\psgrid(0,0)(\paperwidth,-4)
\psdot[dotsize=5pt](0,0)%
\psdot[dotsize=5pt](\paperwidth,0)%
}%
\end{frame}
\end{document}

The option [t] is what I found after some I asked google. When I compile this, the point (0,0) appears to be approximately 1cm below the actual upper left corner of the beamer slide. How can I fix this?

Thanks in advance and best regards
Christian