%%% \vbox height vs. \vtop depth

\type{\vbox} usually inherits its depth from the last box or rule of the vertical
list it contains. Conversely, \type{\vtop} has usually the height of the first box
or rule of the vertical list it contains. However, using whatsits as the
first/last item of the box may lead to surprises.

\beginverbatim
\def\what{\special{}}
\setbox0=\vbox{Aqq \what} \the\ht0, \the\dp0 % 6.83331pt, 1.94444pt
\setbox0=\vtop{\what Aqq} \the\ht0, \the\dp0 % 0.0pt, 8.77776pt
\endverbatim

\type{\vbox} still obeys the rule, although there is a whatsit after the very
last box on the list. But \type{\vtop} has always zero height if its first item is a
whatsit.

\endinput
