bug#29461: Wishlist: better facilities for debugging undo problems

[Noam Postavsky]

Severity: wishlist

See also https://debbugs.gnu.org/cgi/bugreport.cgi?bug=29118#21

To make debugging trouble with undo easier, it would nice to have a way
to "replay" and "rewind" operations to easily see what they do.  And a
way to visualize the meaning of undo list elements without actually
"playing" them, as it's hard to see what a pair of buffer positions
refers to at a glance.

I've written some crude visualization code for markers under
elpa/packages/yasnippet/yasnippet-debug.el.