nested fboxes are collapsed to a single one

[xworld21]

When \fbox is nested, e.g. to create a double border, the current master flattens it to a single box, thus a single border.

\documentclass{article}
\begin{document}
\fbox{\fbox{nested box}}
\end{document}

PDF

XML

<para xml:id="p1">
  <p><text framecolor="black" framed="rectangle">nested box</text></p>
</para>