[development] Forms API "Widgets", AJAX and non-JavaScript

[Rob Thorne]

I've done a couple of projects that needed custom "widgets" to use 
within Forms API, something that you might write into code with 
something like....

    $form['some_text'] = array('#type' => 'textfield', ....);
    $form['event_date'] = drupal_widget_date($title, $default,
    $options....);
    ...

I've done stuff like this for CiviCRM objects like contacts and groups, 
but the idea of getting these kinds of things into reusable functions 
seems pretty attractive, since:

    * It makes it fairly simple to implement some kinds of custom
      JavaScript widgets transparently.
    * You could get consistent "fallback" behavior for non-JavaScript
      capable browsers.
    * The code is easier to understand, and probably more reliable if
      you're doing something unusual.

Has anyone developed anything along this lines?  I'm especially 
interested in finding easier ways to integrate jquery-type widgets for 
more flexible kinds of autocomplete (say, combo-boxes instead of the 
simple pop-up select that autocomplete does now), and integrating safer 
and saner non-JavaScript behavior to a form field that are more consistent.

I'm not sure if I'm being clear enough here, but do any of you have 
ideas similar to this, and how have you implemented them?

Thanks,
Rob