[FMP]

This is a curiosity I wanted to share in case it could be of any use.

I commonly scribble on pdf files generated with LaTeX. In doing so, I noticed that the scribbles on a page with a hyperlink happen to be merged into pdf with the color of the hyperlink.

For instance, running pdflatex on the file:

%%%%%%%%%%
\documentclass{article}
\usepackage{hyperref}

\begin{document}

\section{Black}

\newpage
\section{Green\protect\cite{Wikipedia}}

\newpage
\section{Red\protect\footnote{Footnote.}}

\newpage
\begin{thebibliography}{0}
\bibitem{Wikipedia}
\href{http://en.wikipedia.org/}{Blue}.
\end{thebibliography}

\end{document}
%%%%%%%%%%

generates four pages, respectively with no hyperlink and a green, red, and light blue hyperlinks. Scribbling on this pdf and merging will result on a pdf with scribbles in black, green, read, and light blue. A pdf file so generated with this effect is attached.