Run the test listed below with either "Case 1" or "Case 2" commented.

"Case 1", JComboBox, pops up a list which is normally accessible with VO by navigating it with arrow keys. ���Case 2���, JPopupMenu, pops up the same list, but it is not accessible with arrow keys. Though, VO+"arrow key" seems to work for it.

The problem is likely the same for Swing menus which behave like ���Case 2���. Reproducible with SwingSet2.

(The difference b/w popups is that one of it is a non-focusable window, whereas the second one is a focusable window.)

public class Test {

    public static void main(String[] args) {
        EventQueue.invokeLater(() -> gui());
    }

    private static void gui() {
        JFrame f = new JFrame("frame");

        String[] items = { "One", "Two", "Three", "Four", "Five" };

        // case 1
        JComboBox<String> cb = new JComboBox<>(items);
        f.add(cb);

        // case 2
//        JList<String> l = new JList<>(items);
//        JPopupMenu m = new JPopupMenu();
//        m.add(l);
//        JButton b = new JButton("button");
//        b.addActionListener(e -> m.show(b, 0, 0));
//        f.add(b);

        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }
}