[ale] OT: Detecting changes in HTML form entries

[johnmills at speakeasy.net (John Mills)]

ALErs -

I generate and serve HTML pages which include forms and some embedded
Javascript.  Multiple forms on the same page are traversed by tabs on the
page, each with its own inputs and 'submit' links.

If the user has changed an input field but not saved the form, I would
like to publish and 'alert' before they tab to another form. If necessary
one could test for changes in all forms on the page, but it seems better
to test just the currently selected form.

How can I test for changes when a new tab (or if necessary _any_ tab) is 
selected?

TIA.
 - Mills