Attached a first attempt to make the sidebar collapsible.
The sidebar.js file is the JS script I did, the sidebar.zip file
contains a couple of pages taken from the doc with the sidebar scripts
already included in a <script>.

If you want to try it just extract the files, open the *.html with a
browser and it should work.

This is not supposed to be the final version, I tested it only on FF3
(where it seems to work fine) and on IE6 (where it is as broken as you
would expect). This is also the first time I use JQuery, so any comments
and suggestions are welcomed (both about the code and the result).