Before the MVC pattern I would include UX classes simply by including this at the top of the JS, before Ext.onReady:
Ext.Loader.setConfig({enabl
Ok I found it from this post.
Just need to use Ext.Loader.setPath call at the top of the app controller, e.g.:
Ext.Loader.setPath('Ext.ux', 'extjs/examples/ux');
Ext.application({
name: 'ST',
autoCreateViewport: true,
...
Or wherever you want to put the ux classes, for condensing purposes, the app specific UX classes should be pulled out and stuck in your own folder something like app/ux as the post covers.