verbatim.cls

\def\FV@SetLineWidth{%
  \if@FV@ResetMargins\else
    \advance\leftmargin\@totalleftmargin
  \fi
  \advance\leftmargin\FV@XLeftMargin\relax
  \advance\rightmargin\FV@XRightMargin\relax
  \linewidth\hsize
  %\advance\linewidth-\leftmargin
  %\advance\linewidth-\rightmargin
  \hfuzz\FancyVerbHFuzz\relax}


\def\FV@SingleFrameLine#1{%
%% DG/SR modification end
  \hbox to\z@{%
    %\kern\leftmargin
%% DG/SR modification begin - Jun. 22, 1998
    \ifnum#1=\z@
      \let\FV@Label\FV@LabelBegin
    \else
      \let\FV@Label\FV@LabelEnd
    \fi
    \ifx\FV@Label\relax
%% DG/SR modification end
      \FancyVerbRuleColor{\vrule \@width\linewidth \@height\FV@FrameRule}%
%% DG/SR modification begin - Jun. 22, 1998
    \else
      \ifnum#1=\z@
        \setbox\z@\hbox{\strut\enspace\urlfont\FV@LabelBegin\strut}%
      \else
        \setbox\z@\hbox{\strut\enspace\urlfont\FV@LabelEnd\strut}%
      \fi
      \@tempdimb=\dp\z@
      \advance\@tempdimb -.5\ht\z@
      \@tempdimc=\linewidth
      \advance\@tempdimc -\wd\z@
      %\divide\@tempdimc\tw@
      \ifnum#1=\z@              % Top line
        \ifx\FV@LabelPositionTopLine\relax
          \FancyVerbRuleColor{\vrule \@width\linewidth \@height\FV@FrameRule}%
        \else
          \FV@FrameLineWithLabel
        \fi
      \else                     % Bottom line
        \ifx\FV@LabelPositionBottomLine\relax
          \FancyVerbRuleColor{\vrule \@width\linewidth \@height\FV@FrameRule}%
        \else
          \FV@FrameLineWithLabel
        \fi
      \fi
    \fi
%% DG/SR modification end
    \hss}}


%% DG/SR modification begin - May. 19, 1998
\def\FV@FrameLineWithLabel{%
  \ht\z@\@tempdimb\dp\z@\@tempdimb%
  \FancyVerbRuleColor{%
    \raise 0.5ex\hbox{\vrule \@width\@tempdimc \@height\FV@FrameRule}%
    \raise\@tempdimb\box\z@}}
%% DG/SR modification end


\def\FV@EndListFrame@Lines{%
  \begingroup
    %\vskip 0.5ex
    \baselineskip\z@skip
    \kern\FV@FrameSep\relax
%% DG/SR modification begin - May. 19, 1998
%%    \FV@SingleFrameLine
    \FV@SingleFrameLine{\@ne}%
%% DG/SR modification end
  \endgroup}

\newskip\mytopsep
\setlength{\mytopsep}{4pt plus 2pt minus 3pt}

\def\FV@ListVSpace{%
  \@topsepadd\mytopsep
  \if@noparlist\advance\@topsepadd\partopsep\fi
  \if@inlabel
    \vskip\parskip
  \else
    \if@nobreak
      \vskip\parskip
      \clubpenalty\@M
    \else
      \addpenalty\@beginparpenalty
      \@topsep\@topsepadd
      \advance\@topsep\parskip
      \addvspace\@topsep
    \fi
  \fi
  %\showthe \@topsepadd
  %\showthe \topsep
  %\showthe \partopsep
  %\showthe \parskip
  \global\@nobreakfalse
  \global\@inlabelfalse
  \global\@minipagefalse
  \global\@newlistfalse}

\def\FV@EndList{%
  \FV@ListProcessLastLine
  \FV@EndListFrame
  %\showthe \@topsepadd
  \@endparenv
  \endgroup
  \@endpetrue}

\def\theFancyVerbLine{\sffamily\scriptsize\arabic{FancyVerbLine}}