[thelist] JS: test which submit button was clicked.

[apathetic]

> Nice!  But does it have to be in the onClick?  If the function is called
> by the onSubmit handler, will the .clicked property not work?

When you click a submit button, the onclick even will fire followed by
the onsubmit.  The clicked property will be set onclick, and then the
validation is called onsubmit.

Usually I would advise against using onclick for submit buttons. 
However, in this instance you are specifically testing for a user
clicking a particular button, so onclick is necessary.

Tim