Very nice! There are some rough spots yes, but this looks exactly as I'd
hoped it would, and seems close to being ready for merging.

A few observations, in approximate order of priority:

* What's the copyright and license of showdown? Please include that from
  the original zip file.
* What happens if there are concurrent edits? The CGI.pm modification to
  save an edited wikiwyg part doesn't seem to check if the source file has
  changed in the meantime, so if the part has moved around, it might
  replace the wrong part on saving. I've not tested this.
* The stuff you have in destdir now really belongs in basewiki so it's
  copied over to any destdir.
* Personally, I'm not sure if I need double-click to edit a section in my
  wiki, but I'd love it if the edit form in the cgi could use wikiwyg. Seems
  like both of these could be independent options. Doable, I'm sure?
* It would be good to move as much as possible of the inlined javascript in
  wikiwyg.tmpl out to a separate .js file to save space in the rendered
  pages.
* Both this plugin and the [[Gallery_Plugin_for_Ikiwiki]] are turning out
  to need to add a bunch of pages to the basewiki. I wonder what would be a
  good way to do this, without bloating the basewiki when the plugins arn't
  used. Perhaps the underlaydir concept needs to be expanded so it's a set
  of directories, which plugins can add to. Perhaps you should work with
  arpitjain on this so both plugins can benefit. (The smiley plugin would
  also benefit from this..)
* Is there any way of only loading enough of wikiwyg by default to catch
  the section double-clicks, and have it load the rest on the fly? I'm
  thinking about initial page load time when visiting a wikiwyg-using wiki
  for the first time. I count 230k or so of data that a browser downloads
  in that case..

--[[Joey]]