sidebar in docbook

[Karl Berry]

Hi Patrice (et al.),

Arnold proposed an @sidebar environment in Texinfo, primarily so that he
can get <sidebar><title>Some Title</title>blah blah</sidebar> in Docbook.

For other output formats, he proposed that the output would be like this:

    @cartouche
    @center @b{Some Title}
    blah blah
    @end cartouche

Sadly, I have to say I don't like it.  My problem is simply that
@cartouche @center is not what people actually expect to see as a
"sidebar", so it seems rather a lie; it would be hard to document
coherently and truthfully.  And I can't see a feasible/desirable way to
implement a real sidebar in HTML or Info or TeX.  That's just not how
our output is constructed (being single-column and all), and we don't
want to change the entire Texinfo world merely to suddenly allow
sidebars.

Nevertheless, even if sidebars can't be implemented in general, it seems
like it should be possible in our brave new world for Arnold to do some
combination of Texinfo and Perl such that he gets his sidebars in a
reasonable way.  I admit I am rather at a loss for a real suggestion,
though.

Wdyt?

Thanks,
Karl