Lout and Request for leaders in index entries

[Jeff Kingston]

This apparently innocuous request turns out to be a can of worms, and
I won't be doing it.  However I will file it for implementation in
Nonpareil.  Briefly, the problems are:

* To get leaders Lout uses the @Leaders symbol which is recursive and
  hence not expanded until sizes are calculated.  This means that at
  the time index entries are merged, the entries will contain unexpanded
  symbols.  This is new territory but not impossible by any means; it
  may even be working right now.

* To get the page numbers right justified, even without the leaders,
  we need some structure that works out like this:

       Azaleas &1rt @OneCol { 25, 37 }

  Melding two index entries with this amount of structure would be
  a new departure.  It's not easy to see how to tell Lout to recurse
  into the @OneCol when melding.  It's not the recursion per se, it's
  working out when to recurse and when not to.  Again, probably not
  an impossible problem.

* Lining up the leaders is a nightmare.  In tables of contents there
  is a fixed-width area at the right holding one page number, and
  the leaders are right-justified against this area, hence they all
  line up.  There is no way we can define a reasonable right area
  in indexes, because of cases where multiple page numbers occupy
  a lot of space.  The logical approach is to enlarge the area
  occupied by the page numbers to the next multiple of the leader
  repeat width, but Lout has no mechanism for doing that.

  Another approach would be to put down all possible leaders in
  the background, and overstrike the page numbers while whiting
  out their background.  But this would leave half a leader here
  and there, and also the object structure is too hard when the
  index entry has to be multi-line.
s in
  the background, and overstrike the page numbers while whiting
  out their background.  But this would leave half a leader here
  and there, and also the object structure is too hard when the
  index entry has to be multi-line.

Jeff Kingston