Your situation sounds strangely familiar :)... My opinion is that if I am going to design a form that is going to run in a JavaScript app, I should be able to do so in pure JavaScript. For example:<p><pre><code>  form = new UberUI.form();
  form.append( new UberUI.input( {type: "text", name: "login", label: "Login:", validator: myValidatorFunction} ) );
  ...
  form.show();
</code></pre>
On a different note, jQueryUI is much more theme'able than ExtJS, which is great.