When I try to use the 'tab' key on a group of radio buttons, I can only reach the selected element. When no element is selected, there is no problem. Also, without ToggleGroup, the problem is not present. It seems to be the combination of the two that raises the issue.

Example:

ToggleGroup group = new ToggleGroup();
final RadioButton yes = new RadioButton("Yes");
yes.setToggleGroup(group);
yes.setSelected(true);
final RadioButton no = new RadioButton("No");
no.setToggleGroup(group);