title: onsubmit() does not work
body: <p>Here is something that I find disturbing.  I created a small form, and I'm using AJAX to validate for me.  I have a javascript function authenticate() that works <em>sometimes</em>.</p>
  
  <p><code>&lt;form method="post" action="" id="login_form" onsubmit="authenticate()";&gt;</code></p>
  
  <p><code>// various inputs</code></p>
  
  <p><code>&lt;input type="button" onclick="authenticate()" value="Log In"&gt;</code></p>
  
  <p><code>&lt;/form&gt;</code></p>
  
  <p><code>authenticate()</code> works just fine when I click the button.  However, if I press enter the form is <em>submitted</em>, and it fails.  It also fails if I call onSubmit().  In my debugging, I alert the outgoing texts-- they are identical.  However, the Prototype Ajax function calls it the onSuccess, but there is just no response from the server.  (The server outputs either "Success" or "Failure").</p>
  
  <p>Why the different behaviors for onClick() vs onSubmit()?  The exact same function is called, but the results are different.</p>
  
  <p>Any help would be appreciated.</p>
  
  <p>--Dave</p>