(In reply to comment #0)
> I understand this limitation might be because we need to have uneditable but
> selectable text in the results
David Bailes replies:
"For users of screen readers it is preferable if the list is the
 initial focus, and the OK button is the default button of the dialog,
 so that with the focus in the list, pressing enter presses the OK
 button.
 In fact, the ok button has a blue outline indicating that it is the
 default button, it just doesn't respond to pressing enter."

Testing on latest alphas on both Win and Mac it certainly works now