[tex-eplain] adjusting the space between multiple columns

[John Gabriele]

How can I adjust the space between columns when using \doublecolumns,
while keeping the overall page width constant? That is, when the space
between the two equally wide columns is made bigger, I want the actual
column widths to get smaller.

The relevant Eplain docs (section 4.16) mention \gutter, so I tried:

\gutter = 30 mm

but that doesn't seem to do anything. If I follow the \def\gutterbox
example, and try something like:

\def\gutterbox{\vbox to \dimen0{\vfil\hbox{\hskip 10 mm}\vfil}}

it seems to make the space between columns larger, but also makes a
dark black vertical line on the far right side that cuts off the
column on the right.

My file looks something like this:

=== snip ===
\voffset = -10 mm
\hoffset = -15 mm
\vsize = 10.5 in
\hsize = 7.6 in

%\parindent = 0 mm % not needed here for now.
\nopagenumbers

\input eplain
\doublecolumns
%\gutter = 40 mm % Doesn't seem to make a difference either way.
%\def\gutterbox{\vbox to \dimen0{\vfil\hbox{\vrule height\dimen0}\vfil}}%
%\def\gutterbox{\vbox to \dimen0{\vfil\hbox{\hskip 20 mm}\vfil}}%

% --------------------------------------------------------------------
\centerline{Some centered line}
\vskip 1 mm
\hrule
\vskip 1 mm
\line{maybe something here \hfill here too}

\vskip 15 mm

\centerline{{\it More centered text}}

\vskip 15 mm

\centerline{Something else here perhaps}
\line{{\it xxx \hfill yyy}}

% Do the above maybe 3 more times to fill the column up.

\columnfill

% --------------------------------------------------------------------
\centerline{Some centered line}
\vskip 1 mm
\hrule
\vskip 1 mm
\line{maybe something here \hfill here too}

\vskip 15 mm

\centerline{{\it More centered text}}

\vskip 15 mm

\centerline{Something else here perhaps}
\line{{\it xxx \hfill yyy}}

% A few more of these to fill the rest of this column too.

\bye
=== snip ===

Thanks,
---John