Re: turning off (or enhancing) a couple of new features

[Luc Teirlinck]

Joe Corneli wrote:

   Also, the NEWS file documents changes to the `undo' mechanism,

     ** When the undo information of the current command gets really large
     (beyond the value of `undo-outer-limit'), Emacs discards it and warns
     you about it.

   In fact, Emacs doesn't just warn me, I think it actually prompts me
   and asks if I think it is OK to discard the information.  I always
   say yes, and I would like to know how to get it to always just
   *silently* throw the undo information away.  According to the
   documentation I read, it is basically essential that the info be
   jettisoned whenever we get beyond `undo-outer-limit', so I don't
   see why I should be asked/told about it.

The prompting is controlled by the variable `undo-ask-before-discard'.
This variable is currently set to t for debugging purposes, but it is
scheduled to be turned off before release, because a t value can leak
memory and cause other problems.  The NEWS documents the planned
post-release behavior.

Maybe we should put a section in admin/FOR-RELEASE about changes like
this one that _have_ to be done before release, so we do not
accidentally forget.

Is there a good known reason why you often build up such huge (3 Meg)
single undo entries?  If you do not offhand know the reason for it,
like visiting huge files, it could be due to a bug.

Sincerely,

Luc.