 \relax
 % ---------------------------------------------------------------------
 % Interactive module for retrieving width information for T.R.I.
 % ---------------------------------------------------------------------
 \newbox\testbox\newcount\xxx
 \def\widthof#1{\message{width is: }
 \wwidthof{$\displaystyle#1$}
 \wwidthof{$\scriptstyle#1$}
 \wwidthof{$\scriptscriptstyle#1$}}
 \def\wwidthof#1{\setbox\testbox=\hbox{#1}
 \xxx=\wd\testbox\message{\the\wd\testbox=\the\xxx sp!}}
 \def\endloop{end }\newif\ifOK
 \loop\message{Type in TeX item or say 'end': }
   \read-1 to\answer
   \ifx\answer\endloop\OKfalse\else\OKtrue\fi
   \ifOK\widthof{\answer}
 \repeat
 \end
