Can I make the second button in a form the default button?
The answer seams to be no, there is no built in Drupal method of getting around the problem of the first button in a form being the default when pressing [ENTER].

Here is what I had to do.

I created an extra submit button at the top of my form:

// A submit button that needs to be hidden, it'll be the default rather than one from the list.
$form['hidden-submit'] = array(
  '#type' =&gt; 'submit',
  '#value' =&gt; 'Save',
  '#attributes' =&gt; array('class' =&gt; 'hidden-default-submit'),
);


In the CSS included for the page I added the following belts and braces CSS to hide the extra submit button in as many web browsers as I could test:

.hidden-default-submit {
  position: absolute;
  left: -2000;
  top: -2000;
  width: 0;
  height: 0;
  border: 0;
  margin: 0;
  padding: 0;
}