[texhax] Bad effect when using \doublecolumns

[Karl Berry]

Hi Rodolfo,

    the last line of p.3 falls down beyond the
    page limit, below the page number.

Yes, that's surely a bug, but the underlying problem seems unresolvable
to me, that is, preventing a page break at the beginning of
\doublecolumns material in Eplain.  The \doublecolumns (actually
\@columns) code starts by, among other things, executing the output
routine.  It seems implausible to me to avoid allowing a page break in
those circumstances, though I suppose anything is possible.  Have to
propagate \lastpenalty all the way through and lots more, it seems.

There's also a lot of extra vspace inserted which you would not want in
this context, although that is relatively easily controllable.

So, to get the output you want, i.e.,

<double column text>
<single column section heading>
<more double column text>

I think you have to force a page break before the \beginsection.  The
existing Eplain \doublecolumns is not set up to be executed in such a
place, and I can't see how to feasibly make it so.  Though if anyone
wants to take up the TeX challenge, of course that would be great :).

sorry,
karl