An extra widget has been added to arboreal, to support collapsible trees.
The code is coming from: http://www.silverstripe.com/downloads/tree/ and is as unintrusive as possible.
It has a BSD license.

Some javascript and css needs to be available. It has been copied into the skin as: tree.js and tree.css
A bunch of graphics is needs, has also been put into the arboreal skin.

One modification has to be made to tree.js to register it with the plone 'onload' machinery.

The js and css files are registered with the portal_css and portal_javascript tool at quickinstall time.

A widget has been added to 'abr_multiselection_widget', a format of type 'collapsed' can now be used.

A macro has been added to 'abr_tree_view_macro', that can render a tree view, useful for searchform. 
However, this one is a bit specific.
It expects a recursive list of hashes: [{'path': '/arbo-path', 'title': 'a title', 'subs: [ <the recursive list> ]}]


