Boxes

If you write

\newcommand{\mchunk}[1]{\chunk{\makebox(30,15){#1}}}
\newenvironment{mbundle}[1]{\begin{bundle}{\makebox(30,15){#1}}}{\end{bundle}}
\begin{mbundle}{xxx}
\mchunk{aaa}
\chunk{
        \begin{mbundle}{yyy}
        \mchunk{bbb}
        \mchunk{ddd}
        \end{fbundle}}
\mchunk{ccc}
\end{mbundle}
you get
\begin{bundle}{\makebox(30,15){xxx}}
\chunk{\makebox(30,15){aaa}}
\chunk{
\begi...
...nk{\makebox(30,15){ddd}}
\end{bundle}}
\chunk{\makebox(30,15){ccc}}\end{bundle}
instead of
\begin{bundle}{xxx}
\chunk{aaa}
\chunk{
\begin{bundle}{yyy}
\chunk{bbb}
\chunk{ddd}
\end{bundle}}
\chunk{ccc}
\end{bundle}
.

\newcommand{\fchunk}[1]{\chunk{\framebox(30,15){#1}}}
\newenvironment{fbundle}[1]{\begin{bundle}{\framebox(30,15){#1}}}{\end{bundle}}
\begin{fbundle}{xxx}
\fchunk{aaa}
\chunk{
        \begin{fbundle}{yyy}
        \fchunk{bbb}
        \fchunk{ddd}
        \end{fbundle}}
\fchunk{ccc}
\end{fbundle}

\begin{bundle}{\framebox (30,15){xxx}}
\chunk{\framebox (30,15){aaa}}
\chunk{
\...
...framebox (30,15){ddd}}
\end{bundle}}
\chunk{\framebox (30,15){ccc}}\end{bundle}




\begin{fbundle}{xxx}
\fchunk{aaa}
\chunk{\fbox{
        \begin{fbundle}{yyy}
        \fchunk{bbb}
        \fchunk{ddd}
        \end{fbundle}}}
\fchunk{ccc}
\end{fbundle}

\begin{bundle}{\framebox (30,15){xxx}}
\chunk{\framebox (30,15){aaa}}
\chunk{\fb...
...framebox(30,15){ddd}}
\end{bundle}}}
\chunk{\framebox (30,15){ccc}}\end{bundle}