o  A new project under development (not yet out on CPAN)
   Substitution::Tracking might superceed the Rep.pm
   module inside the Emacs::Rep distribution.  Consider
   re-writing rep.pl and rep.el to use it, if there's any
   advantage.

o  The emacs side of Emacs::Rep (rep.el) has no tests.
   Find or write an elisp test framework and fix that.
   Q: did the nxhtml work get included in Emacs 24?  It
   has a test framework of sorts (though it does not
   conform to the TAP standard).

o  Feature: a rep-redo command to undo the effect of a rep-undo.

o  Investigate and document potential confusions between
   the emacs standard undo system and the rep-undo system.

o  After applying a set of changes to a buffer, it let's
   you apply the changes again (or a different set of
   change) even before changes have been accepted.  At
   present, rep-undos "work" afterwards, but in a very
   peculiar way that would have to be called buggy.
   Reverts can still be done back to the original state,
   though.

   "apply" should check the other windows minor-mode-list
   for the presence of rep-modified-mode, and refuse to
   act, warning the user that they need to accept changes
   before doing an apply again.

o  rep.el: write a debugging routine that tells you
   the state of the rep overlays at a particular point
   (a beefed up version of "what", perhaps).