This is the Roo Javasript library - RooJS

It is based on a fork of the original ExtJS1 code, and the pre-1.0 resources which where available
under a LGPL and BSD licences

Quite a bit has changed since the original Fork (see CHANGES.txt it's updated occasionally)

In theory it should be API compatible with ExtJS1, however it includes quite a few fixes and better
security that ExtJS in general.