I've created my own beamer theme which uses a vertical shading for the background, but whenever I'm using a plain frame a thin white strip is left at the top of the page.
I've created a minimum working example that shows the problem even with the default beamer theme:
\documentclass[]{beamer}
\setbeamertemplate{background canvas}[vertical shading][bottom=red,top=red]
\begin{document}
\frame[plain]{\titlepage}
\end{document}
Does anybody know a solution to this?
Btw, I'm using beamer version 3.0.1.