JBR-5684 Focus state is broken after closing of modal dialog in an inactive application

src/java.desktop/share/classes/java/awt/KeyboardFocusManager.java

@@ -26,6 +26,7 @@ package java.awt;
 
 import java.awt.event.FocusEvent;
 import java.awt.event.InputEvent;
+import java.awt.event.InvocationEvent;
 import java.awt.event.KeyEvent;
 import java.awt.event.WindowEvent;
 
@@ -2802,11 +2803,8 @@ public abstract class KeyboardFocusManager
                 if (hwFocusRequest.lightweightRequests.size() > 0) {
                     currentLightweightRequests =
                         hwFocusRequest.lightweightRequests;
-                    EventQueue.invokeLater(new Runnable() {
-                            public void run() {
-                                processCurrentLightweightRequests();
-                            }
-                        });
+                    SunToolkit.postPriorityEvent(new InvocationEvent(source,
+                            KeyboardFocusManager::processCurrentLightweightRequests));
                 }
 
                 // 'opposite' will be fixed by

test/jdk/jb/java/awt/Focus/ComplexFocusSequence.java

@@ -0,0 +1,155 @@
+/*
+ * Copyright 2023 JetBrains s.r.o.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import java.awt.*;
+import java.awt.event.*;
+import java.io.File;
+import java.util.concurrent.*;
+import java.util.concurrent.locks.LockSupport;
+import javax.swing.*;
+
+/**
+ * @test
+ * @summary Regression test for JBR-5684 Focus state is broken after closing of modal dialog in an inactive application
+ * @key headful
+ */
+
+public class ComplexFocusSequence {
+    private static final CompletableFuture<Boolean> success = new CompletableFuture<>();
+
+    private static Robot robot;
+    private static JFrame frame;
+    private static JButton dialogButton;
+    private static Process otherProcess;
+
+    public static void main(String[] args) throws Exception {
+        robot = new Robot();
+        try {
+            SwingUtilities.invokeAndWait(ComplexFocusSequence::initUI);
+            launchOtherProcess();
+            robot.delay(1000);
+            clickAt(200, 500); // make sure other process'es window is activated
+            robot.delay(1000);
+            SwingUtilities.invokeLater(ComplexFocusSequence::showInactiveDialog);
+            robot.delay(1000);
+            clickOn(dialogButton);
+            robot.delay(1000);
+            typeEnter();
+            success.get(3, TimeUnit.SECONDS);
+        } finally {
+            SwingUtilities.invokeAndWait(ComplexFocusSequence::disposeUI);
+        }
+    }
+
+    private static void initUI() {
+        frame = new JFrame("ComplexFocusSequence");
+        JTextField textField = new JTextField(30);
+        textField.addActionListener(e -> success.complete(true));
+        frame.add(textField);
+        frame.pack();
+        frame.setLocation(100, 100);
+        frame.setVisible(true);
+    }
+
+    private static void showInactiveDialog() {
+        JComboBox<?> cb = new JComboBox<>();
+        cb.setEditable(true);
+        JDialog d = new JDialog(frame, true);
+        d.addWindowFocusListener(new WindowAdapter() {
+            @Override
+            public void windowGainedFocus(WindowEvent e) {
+                cb.requestFocus();
+            }
+        });
+        d.add(cb, BorderLayout.CENTER);
+        dialogButton = new JButton("Close");
+        dialogButton.addActionListener(ee -> {
+            d.dispose();
+            spinEventLoop();
+        });
+        d.add(dialogButton, BorderLayout.SOUTH);
+        d.pack();
+        d.setLocationRelativeTo(frame);
+        d.setVisible(true);
+    }
+
+    private static void spinEventLoop() {
+        EventQueue eq = Toolkit.getDefaultToolkit().getSystemEventQueue();
+        SecondaryLoop loop = eq.createSecondaryLoop();
+        new Thread(() -> {
+            do {
+                LockSupport.parkNanos(100_000_000);
+            } while (!loop.exit());
+        }).start();
+        loop.enter();
+    }
+
+    private static void disposeUI() {
+        if (frame != null) frame.dispose();
+        if (otherProcess != null) otherProcess.destroyForcibly();
+    }
+
+    private static void launchOtherProcess() throws Exception {
+        otherProcess = Runtime.getRuntime().exec(new String[]{
+                System.getProperty("java.home") + File.separator + "bin" + File.separator + "java",
+                "-cp",
+                System.getProperty("java.class.path"),
+                "ComplexFocusSequenceChild"
+        });
+        if (otherProcess.getInputStream().read() == -1) {
+            throw new RuntimeException("Error starting process");
+        }
+    }
+
+    private static void clickAt(int x, int y) {
+        robot.mouseMove(x, y);
+        robot.mousePress(InputEvent.BUTTON1_DOWN_MASK);
+        robot.mouseRelease(InputEvent.BUTTON1_DOWN_MASK);
+    }
+
+    private static void clickOn(Component component) {
+        Point location = component.getLocationOnScreen();
+        clickAt(location.x + component.getWidth() / 2, location.y + component.getHeight() / 2);
+    }
+
+    private static void typeEnter() {
+        robot.keyPress(KeyEvent.VK_ENTER);
+        robot.keyRelease(KeyEvent.VK_ENTER);
+    }
+}
+
+class ComplexFocusSequenceChild {
+    public static void main(String[] args) {
+        SwingUtilities.invokeLater(() -> {
+            JFrame f = new JFrame("ComplexFocusSequence 2");
+            f.addWindowFocusListener(new WindowAdapter() {
+                @Override
+                public void windowGainedFocus(WindowEvent e) {
+                    System.out.println();
+                }
+            });
+            f.setBounds(100, 400, 200, 200);
+            f.setVisible(true);
+        });
+    }
+}