-\def\Maskbox#1#2#3#4#5#6{{\setbox2=\hbox{#6}\ltj@tablshift\z@
-\setbox0=\hbox{\@ascgrp#3}%
-\dimen0=#1\@setdim{\dimen0}{\wd0}\dimen1=#2\@setdim{\dimen1}{\ht0}%
-\ifx#4c\skip0=0pt plus1fil\skip1=\skip0\fi
-\ifx#4r\skip0=0pt plus1fil\skip1=0pt\fi
-\ifx#4l\skip1=0pt plus1fil\skip0=0pt\fi
-\hbox{\hbox to0pt{\hbox to\dimen0{\leaders\vbox to\dimen1{\leaders
-\hbox{\@ascgrp#3}\vfil}\hfil}\hss}%
-\vrule width#5\vbox to\dimen1{\hrule height#5\vfil
-\dimen3=#5\advance\dimen0-2\dimen3\advance\dimen0 .15pt
-\hbox to\dimen0{\hskip\skip0\box2\hskip\skip1}%
-\vfil\hrule height#5}\vrule width#5}}}
+\def\Maskbox#1#2#3#4#5#6{{%
+ \setbox0=\hbox{\ltj@yablshift\z@\ltj@tablshift\z@ \@ascgrp#3}%
+ \dimen0=#1\@setdim{\dimen0}{\wd0}\dimen1=#2\@setdim{\dimen1}{\ht0}%
+ \ifx#4c\skip0=0pt plus1fil\skip1=\skip0\fi
+ \ifx#4r\skip0=0pt plus1fil\skip1=0pt\fi
+ \ifx#4l\skip1=0pt plus1fil\skip0=0pt\fi
+ \leavevmode
+ \hbox{\hbox to0pt{\hbox to\dimen0{\leaders\vbox to\dimen1{\leaders
+ \box0\vfil}\hfil}\hss}%
+ \vrule width#5\vbox to\dimen1{\hrule height#5\vfil
+ \dimen3=#5\advance\dimen0-2\dimen3\advance\dimen0 .15pt
+ \hbox to\dimen0{\hskip\skip0\relax#6\hskip\skip1}%
+ \vfil\hrule height#5}\vrule width#5}}}
+
+%% shadebox environment
+\def\shadebox{\par\vspace{.3\baselineskip}%
+ \@saveybaselineshift\ltj@yablshift sp\ltj@yablshift\z@
+ \@savetbaselineshift\ltj@tablshift sp\ltj@tablshift\z@
+ \dimen0\linewidth \advance\dimen0-20pt
+ \advance\dimen0-2\fboxrule \advance\dimen0-\shaderule
+ \setbox\@tempboxa=\hbox\bgroup\minipage{\dimen0}%
+ \ltj@yablshift\@saveybaselineshift \ltj@tablshift\@savetbaselineshift}