Parbox

Hide an artificial math.

<..latex math..>+
 \long\def\:temp#1#2[#3]#4#5{%
   \leavevmode
   \@pboxswfalse
   \setlength\@tempdima{#4}%
   \@begin@tempboxa\vbox{\hsize\@tempdima\@parboxrestore#5\@@par}%
     \ifx<.new @iiiparbox.>#2\else
     \ifx<.old @iiiparbox.>#2\else
       \setlength\@tempdimb{#2}%
       \def\@parboxto{to\@tempdimb}%
     \fi\fi
      \def\v:TBL{#1}%
     \if#1b\vbox
     \else\if #1t\vtop
     \else\ifmmode\vcenter
     \else\@pboxswtrue <.hide parbox math.>$\vcenter
     \fi\fi\fi
     \@parboxto{\let\hss\vss\let\unhbox\unvbox
        \csname bm@#3\endcsname}%
     \if@pboxsw \m@th$\fi
   \@end@tempboxa}
 \HLet\@iiiparbox=\:temp
 -_-_-

<..hide parbox math..>
 \expandafter\everymath\expandafter{\expandafter
            \everymath\expandafter{\the\everymath}}%
 -_-_-

<..old @iiiparbox..>
 \@empty -_-_-

<..new @iiiparbox..>
 \relax -_-_-