I need to append some additional notes to my 2007/10/03 Wt Configuration Guide article.
As mentioned in the Wt Ext Widget deployment notes, the Wt toolkit makes use of libraries from Ext JS. There are notes at the bottom of the Wt page itemizing the files needed from the JS Ext 1.1 .zip file.
As a side note, all things Ajax can be referenced one way or another starting at the ajaxian web site. Maybe not quite the truth. More all things Ajax at AjaxPatterns... if you want to get under the hood.