NPE on Windows 10 when showing a popup without an invoker

[eduhoribe]

After #626 released on 3.2.1 a NPE is thrown when showing a popup without an invoker on Windows 10 (or maybe Windows != 11?).

Sample code to reproduce:

import com.formdev.flatlaf.FlatDarkLaf;

import javax.swing.*;
import javax.swing.border.EmptyBorder;
import java.awt.*;

public class Windows10PopupNPE {

    public static void main(String[] args) {
        FlatDarkLaf.setup();

        SwingUtilities.invokeLater(() -> new Form().setVisible(true));
    }

    static class Form extends JFrame {
        public Form() {
            JButton button1 = new JButton("Open popup with show()");
            button1.addActionListener(e -> {
                JPopupMenu popup = new JPopupMenu();
                popup.add(new JLabel("Opened with show()"));
                popup.show(button1, 0, button1.getHeight());
            });

            JButton button2 = new JButton("Open popup with setVisible()");
            button2.addActionListener(e -> {
                JPopupMenu popup = new JPopupMenu();
                popup.add(new JLabel("Opened with setVisible()"));
                popup.setInvoker(button2);
                Point locationOnScreen = button2.getLocationOnScreen();
                popup.setLocation(locationOnScreen.x, locationOnScreen.y + button2.getHeight());
                popup.setVisible(true);
            });

            JButton button3 = new JButton("Open popup with setVisible() but without an invoker");
            button3.addActionListener(e -> {
                JPopupMenu popup = new JPopupMenu();
                popup.add(new JLabel("Opened with setVisible()"));
                Point locationOnScreen = button3.getLocationOnScreen();
                popup.setLocation(locationOnScreen.x, locationOnScreen.y + button3.getHeight());
                popup.setVisible(true);
            });

            Container contentPane = getContentPane();
            if (contentPane instanceof JPanel) {
                ((JPanel) contentPane).setBorder(new EmptyBorder(10, 10, 10, 10));
            }
            contentPane.setLayout(new FlowLayout());
            contentPane.add(button1);
            contentPane.add(button2);
            contentPane.add(button3);

            pack();
            setLocationRelativeTo(null);

            setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        }
    }
}

Stacktrace:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
	at javax.swing.SwingUtilities.getWindowAncestor(SwingUtilities.java:137)
	at com.formdev.flatlaf.ui.FlatPopupFactory.overlapsHeavyWeightComponent(FlatPopupFactory.java:397)
	at com.formdev.flatlaf.ui.FlatPopupFactory.getPopup(FlatPopupFactory.java:107)
	at javax.swing.plaf.PopupMenuUI.getPopup(PopupMenuUI.java:61)
	at com.formdev.flatlaf.ui.FlatPopupMenuUI.getPopup(FlatPopupMenuUI.java:216)
	at javax.swing.JPopupMenu.showPopup(JPopupMenu.java:837)
	at javax.swing.JPopupMenu.setVisible(JPopupMenu.java:790)
	at org.example.Windows10PopupNPE$Form.lambda$new$2(Windows10PopupNPE.java:42)
	at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
	at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
	at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
	at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:262)
	at java.awt.Component.processMouseEvent(Component.java:6539)
	at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
	at java.awt.Component.processEvent(Component.java:6304)
	at java.awt.Container.processEvent(Container.java:2239)
	at java.awt.Component.dispatchEventImpl(Component.java:4889)
	at java.awt.Container.dispatchEventImpl(Container.java:2297)
	at java.awt.Component.dispatchEvent(Component.java:4711)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4904)
	at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4535)
	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4476)
	at java.awt.Container.dispatchEventImpl(Container.java:2283)
	at java.awt.Window.dispatchEventImpl(Window.java:2746)
	at java.awt.Component.dispatchEvent(Component.java:4711)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:760)
	at java.awt.EventQueue.access$500(EventQueue.java:97)
	at java.awt.EventQueue$3.run(EventQueue.java:709)
	at java.awt.EventQueue$3.run(EventQueue.java:703)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:84)
	at java.awt.EventQueue$4.run(EventQueue.java:733)
	at java.awt.EventQueue$4.run(EventQueue.java:731)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

[eduhoribe]

Also tested on the version 3.2.4 which fixes a similar bug for Linux with Wayland and Java 21

[DevCharly]

Many thanks for reporting and fixing 👍

It is Windows 10 only.

Fixed in 3.2.5