我试着用 JCombobox 内部 JPopupMenu ，但如果不成功，当用户单击标签时，弹出窗口将可见，

label = new JLabel();
 label.addMouseListener(this);

这是标签代码，带有鼠标侦听器 mousePressed 以及 mouseClicked 事件它确实显示和隐藏弹出菜单，在我的菜单里面 JPanel 其中包含 ButtonGroup ，单击按钮显示不同的 JPanel 在面板的中心，面板和弹出菜单代码的缩写如下

popupPanel = new JPanel();
    popupPanel.setLayout(new BorderLayout());

    menu = new JPopupMenu();
    menu.add(BorderLayout.CENTER, popupPanel);
    menu.pack();
    menu.addPopupMenuListener(this);

弹出面板包含我上面提到的按钮组，当单击其中一个按钮时，它会显示出来

color_combo_panel = new JPanel();
    color_combo_panel.setLayout(new GridBagLayout());

    color_combo = new JComboBox<>();
    color_combo.addItem(Color.RED.toString());
    color_combo.addItem(Color.BLUE.toString());
    color_combo.addItem(Color.CYAN.toString());
    color_combo.setRenderer(new ColorRenderer());

面板包含 JCombobox ，问题从这里开始，当我点击组合框选择颜色时， JPopupMenu 关上，在另一只手上 JCombobox 选择什么都不做，我的问题是，我怎么能强迫弹出菜单保持可见，用鼠标和弹出的听众我已经强迫它保持可见，但结果我得到了 IllegalComponentStateException ，组件必须显示在屏幕上，我发现的问题类似于我的，但它没有提供相关的解决方案，加上这个行为是作为一个错误提交这里。
如有任何有用的建议，我将不胜感激
编辑@camickr要求的最小可复制示例

public class PopupTest {

public static void main(String[] args) {

    JFrame frame = new JFrame();
    frame.setSize(new Dimension(500, 500));
    frame.setLayout(new GridBagLayout());
    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    frame.add(new ColorCombo());
    frame.setVisible(true);

}

static class ColorCombo extends JComboBox {

    private static final long serialVersionUID = 2L;

    public ColorCombo() {
        setPreferredSize(new Dimension(200, 30));
    }

    @Override
    public void updateUI() {
        ComboBoxUI cui = (ComboBoxUI) UIManager.getUI(this);
        if (cui instanceof MetalComboBoxUI) {
            cui = new MetalBrushComboBoxUI();
        } else {
            cui = new BasicBrushComboboxUI();
        }
        setUI(cui);
    }

    class MetalBrushComboBoxUI extends MetalComboBoxUI {
        @Override
        protected ComboPopup createPopup() {
            return new ColorPopup(comboBox);
        }
    }

    class BasicBrushComboboxUI extends BasicComboBoxUI {

        @Override
        protected ComboPopup createPopup() {
            return new ColorPopup(comboBox);
        }
    }

    class ColorPopup extends MouseAdapter implements ComboPopup, ActionListener {

        private JList list = new JList();
        private JComboBox comboBox;
        private JPopupMenu popupMenu;
        private JPanel container, first_color_panel;

        public ColorPopup(JComboBox comboBox) {
            this.comboBox = comboBox;

            container = new JPanel();
            container.setLayout(new BorderLayout());

            JToggleButton first_button = new JToggleButton();
            first_button.setBorder(BorderFactory.createLineBorder(Color.BLACK, 2, false));
            first_button.setPreferredSize(new Dimension(20, 20));
            first_button.setBackground(Color.WHITE);
            first_button.addActionListener(this);
            first_button.setActionCommand("color1");

            ButtonGroup buttonGroup = new ButtonGroup();
            buttonGroup.add(first_button);

            JPanel northPanel = new JPanel();
            northPanel.setLayout(new FlowLayout(FlowLayout.LEFT));
            northPanel.add(first_button);

            first_color_panel = new JPanel();
            first_color_panel.setLayout(new GridBagLayout());

            JComboBox<String> color_combo = new JComboBox<>();
            color_combo.setPreferredSize(new Dimension(120, 30));
            for (String color : getColors().keySet())
                color_combo.addItem(color);
            color_combo.setRenderer(new ColorRenderer());
            color_combo.addActionListener(this);
            color_combo.setActionCommand("color1_ground");

            first_color_panel.add(color_combo);

            container.add(northPanel, BorderLayout.NORTH);

            popupMenu = new JPopupMenu();
            popupMenu.add(BorderLayout.CENTER, container);
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            boolean isSet = container.getComponents().length == 2;
            if ("color1".equals(e.getActionCommand())) {
                if (isSet)
                    container.remove(1);
                container.add(first_color_panel, BorderLayout.CENTER);
            }
            container.revalidate();
            popupMenu.repaint();
        }

        @Override
        public void show() {
            this.container.setPreferredSize(new Dimension(this.comboBox.getWidth(), 100));
            popupMenu.add(BorderLayout.CENTER, container);
            popupMenu.pack();
            popupMenu.show(this.comboBox, 0, this.comboBox.getHeight());
        }

        @Override
        public void hide() {
            popupMenu.setVisible(false);
        }

        @Override
        public boolean isVisible() {
            return popupMenu.isVisible();
        }

        @Override
        public JList getList() {
            return list;
        }

        @Override
        public MouseListener getMouseListener() {
            return this;
        }

        @Override
        public MouseMotionListener getMouseMotionListener() {
            return this;
        }

        @Override
        public KeyListener getKeyListener() {
            return null;
        }

        @Override
        public void uninstallingUI() {

        }

        @Override
        public void mouseClicked(MouseEvent e) {
            comboBox.requestFocus();
            toggle();
        }

        private void toggle() {
            if (isVisible()) {
                hide();
            } else {
                show();
            }

        }

        private Map<String, Color> getColors() {
            Map<String, Color> colors = new HashMap<>();
            colors.put("Red", Color.RED);
            colors.put("blue", Color.BLUE);
            colors.put("green", Color.GREEN);
            colors.put("Yellow", Color.YELLOW);
            return colors;
        }

        class ColorRenderer extends JPanel implements ListCellRenderer<String> {

            @Override
            public Component getListCellRendererComponent(JList<? extends String> list, String value, int index, boolean isSelected, boolean cellHasFocus) {
                JPanel panel = new JPanel();
                panel.setLayout(new BorderLayout(3, 3));
                panel.setBorder(BorderFactory.createCompoundBorder(getBorder(),
                        BorderFactory.createEmptyBorder(0, 0, 3, 0)));

                JLabel label = new JLabel();
                label.setOpaque(true);
                label.setPreferredSize(new Dimension(20, label.getHeight()));
                label.setBackground(getColors().get(value));

                JLabel text = new JLabel();
                text.setText(value);

                panel.add(label, BorderLayout.WEST);
                panel.add(text, BorderLayout.CENTER);

                return panel;
            }
        }

    }
}}