\newbox\microbox
\newdimen\microw
\font\microa=microa
\setbox\microbox=\vbox{\hbox{%
\microa !()+}}
\microw=\wd\microbox
\setbox\microbox=\hbox{\vbox{\hsize=\microw
\parskip=0pt\offinterlineskip\parindent0pt
\hbox{\microa !()+}}}
\ifx\parbox\undefined
    \def\setmicro{\box\microbox}
\else
    \def\setmicro{\parbox{\wd\microbox}{\box\microbox}}
\fi
