+% However, if \package{slowbox} sees a slow box \<tag> it's not noticed
+% before, it always typesets the box contents, and saves the measurements for
+% later.
+%
+% \begin{demo}{Slow boxes}
+%\newcommand{\pic}
+% {\parbox[t]{20mm}
+% {Just pretend that there's a picture
+% here that would take aaaages to draw.}}
+%--
+%\begin{slowbox*}{show}
+% \pic
+%\end{slowbox*}
+%--
+%\begin{slowbox}{hide}
+% \pic
+%\end{slowbox}
+%--
+% \end{demo}
+%