The qForms API was designed to be easily expandable. There are two main parts to the qForms APIthe core API and the extension libraries. Custom libraries can be created to extend the core API set. Several libraries are included with the qForms API, including: a validation library, a form field extension library (which includes methods for moving items from one select box to another), a common library of function and even a libraries for handling dealing with bit masking. Custom libraries will be available for download off the qForms site.
It's important to remember that the qForms API is open source and offered free to the development community. In order for qForms JSAPI to keep improving and growing, please make sure to share any custom libraries and methods that you've created, so the entire community can benefit!
I think you'll find that the qForms API greatly eases the process of client-side form programming.