The ExtJS Library provides THE BEST widgets of any JS library out there, but it is incredibly difficult to use it for progressive enhancement of existing markup.
For instance, to take a HTML unordered list and turn it into a ExtJS tree... Good luck!
It is easy enough to create a tree and have the javascript inject all the DOM nodes, but to use ExtJS to modify existing markup is enough to drive you bonkers!
-sD-
Dr. Scotty Delicious, DFPA.
