Collapsible tree

Collapsible tree


Howdy!
It's there a component in jQuery UI that allows me to build a
collapsible tree, like in a file explorer?
I need to be able to customize the several tree nodes, and drag and
drop stuff onto them.
Node in different level have different behaviors.
I'm building a small workflow engine, which will enable to user the
specify a set of task to run hierarchically.
Something like this:
http://www.howtocreate.co.uk/tutorials/jsexamples/collapseList.html
Thanks.