Subject: bug#13837: 24.2; Make it possible to turn whitespace-mode only when there are no existing problems

From: Stefan Monnier <[email-masked]>
Date: Fri, 01 Mar 2013 22:02:28 -0500

>> (add-function :after-while (default-value 'whitespace-enable-predicate)
>>               #'whitespace-check-cleanliness)
> Emacs 24 doesn't seem to have add-function;

We're talking about changing whitespace.el, so I take it for granted
that this can be a "trunk-only" solution.

        Stefan