#191 xetex/dvipdfm can't produce opaque white background

[Nico Schlömer]

With

\documentclass{article}

\usepackage{xcolor}
\pagecolor{green}

\begin{document}
abc
\end{document}

one can produce a PDF with an opaque green background. When changing the color to white

\pagecolor{white}

the background is set to transparent by dvipdfm here. pdflatex produces an opaque white background.

The problem occurred to me when converting a PDF to SVG, and being unable to a solid white background.