We have a form - it's just a VBox with the defaultButton property set and a couple of date fields, radio buttons and other controls. No tabIndex set yet.
Clicking on a radio button causes the default button to highlight and function as expected. Right arrow to the next radio button in the group, and the default button is no longer highlighted! Also click in the editable date field, and the default button is not highlighted. Are these bugs, or am I not following some recipe?