If left NULL, HTML Purifier will attempt to instantiate a <code>csstidy</code>
class to use for internal cleaning. This will usually be good enough.
However, for trusted user input, you can set this to <code>false</code> to
disable cleaning. In addition, you can supply your own concrete implementation
of Tidy's interface to use, although I don't know why you'd want to do that.
--# vim: et sw=4 sts=4