I had this question after this discussion. The problem is Mac Preview behaves differently than Adobe acrobat reader DC. The pdf is compile with pdflatex. Here is MWE.
\documentclass{article}
\usepackage{hyperref}
\usepackage{xcolor}
\hypersetup{pdftitle={main.pdf},
colorlinks=false,
linkbordercolor=red
}
\begin{document}
\tableofcontents
\section{test}
\section{test2}
This is testing hyperref
\end{document}
and the results in preview and Adobe acrobat reader are
and
respectively. This also looks perfectly alright in the internal viewer of my editor (texstudio).
Que: why can't I see red boundaries in preview?
