Can you put on the wiki ?
The only problem is that the height of the columnrule is fixed, which
doesn't look right with balanced columns :-( Would it be possible to
force this MPgraphic{columnrule} to use the actual height of the
balanced columns, instead of going all the way down to the bottom of the
page regardless of the actual column height? Or should I give up on this
question? (I'm on MkII/XeTeX for this project, so no lua based solution
possible.)