** Distribute a bar cursor of width > 1 evenly between the two glyphs
on each side of the bar (what to do at the edges?).
-** buffer-offer-save should be a permanent local.
-
** revert-buffer should eliminate overlays and the mark.
For related problems consult the thread starting with
http://lists.gnu.org/archive/html/emacs-devel/2005-11/msg01346.html