Pourquoi mon Swing JTabbedPane ne met-il pas à jour son apparence après avoir modifié l'UIManager ?

Window windows[] = Frame.getWindows();
for(Window window : windows) {
    SwingUtilities.updateComponentTreeUI(window);
}

public class JTabbedText {

    // ... (code omitted for brevity)

    private static JToolBar createToolBar(final Component parent) {
        // ... (code omitted for brevity)

        combo.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent ae) {
                int index = combo.getSelectedIndex();
                try {
                    UIManager.setLookAndFeel(
                        available[index].getClassName());

                    // Update the UI of all windows
                    Window[] windows = Window.getWindows();
                    for (Window window : windows) {
                        SwingUtilities.updateComponentTreeUI(window);
                    }
                } catch (Exception e) {
                    e.printStackTrace(System.err);
                }
            }
        });

        // ... (code omitted for brevity)
    }

    // ... (code omitted for brevity)
}