JBR-5984: IM's candidate window is placed under popup windows.

- Implements the optional method [NSTextInputClient windowLevel] to tell the macOS IM subsystem correct level of the window;
- Adds a regression test ImWindowIsPlacedUnderPopup5984.java.

(cherry picked from commit 5a91aae9c2)

src/java.desktop/macosx/native/libawt_lwawt/awt/AWTView.m

@@ -35,6 +35,7 @@
 #import "JNIUtilities.h"
 #import "jni_util.h"
 #import "PropertiesUtilities.h"
+#import "sun_lwawt_macosx_CPlatformWindow.h"
 
 #import <Carbon/Carbon.h>
 
@@ -1096,6 +1097,43 @@ static jclass jc_CInputMethod = NULL;
 #define GET_CIM_CLASS_RETURN(ret) \
     GET_CLASS_RETURN(jc_CInputMethod, "sun/lwawt/macosx/CInputMethod", ret);
 
+- (NSInteger) windowLevel
+{
+#ifdef IM_DEBUG
+    fprintf(stderr, "AWTView InputMethod Selector Called : [windowLevel]\n");
+#endif // IM_DEBUG
+
+    NSWindow* const ownerWindow = [self window];
+    if (ownerWindow == nil) {
+        return NSNormalWindowLevel;
+    }
+
+    const NSWindowLevel ownerWindowLevel = [ownerWindow level];
+    if ( (ownerWindowLevel != NSNormalWindowLevel) && (ownerWindowLevel != NSFloatingWindowLevel) ) {
+        // the window level has been overridden, let's believe it
+        return ownerWindowLevel;
+    }
+
+    AWTWindow* const delegate = (AWTWindow*)[ownerWindow delegate];
+    if (delegate == nil) {
+        return ownerWindowLevel;
+    }
+
+    const jint styleBits = [delegate styleBits];
+
+    const BOOL isPopup = ( (styleBits & sun_lwawt_macosx_CPlatformWindow_IS_POPUP) != 0 );
+    if (isPopup) {
+        return NSPopUpMenuWindowLevel;
+    }
+
+    const BOOL isModal = ( (styleBits & sun_lwawt_macosx_CPlatformWindow_IS_MODAL) != 0 );
+    if (isModal) {
+        return NSFloatingWindowLevel;
+    }
+
+    return ownerWindowLevel;
+}
+
 - (void) insertText:(id)aString replacementRange:(NSRange)replacementRange
 {
 #ifdef IM_DEBUG

test/jdk/jb/java/awt/im/ImWindowIsPlacedUnderPopup5984.java

@@ -0,0 +1,141 @@
+/*
+ * Copyright (c) 2023, JetBrains s.r.o.. All rights reserved.
+ * 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.
+ */
+
+
+/*
+ * @test
+ * @summary A manual test of JBR-5984 bug checks if an IM's window is placed above Swing's/AWT's popups
+ * @author Nikita Provotorov
+ * @requires (os.family == "mac")
+ * @key headful
+ * @run main/othervm/manual -Xcheck:jni ImWindowIsPlacedUnderPopup5984
+ */
+
+
+import javax.swing.*;
+import java.awt.*;
+import java.awt.event.WindowAdapter;
+import java.awt.event.WindowEvent;
+import java.lang.reflect.InvocationTargetException;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+
+
+public class ImWindowIsPlacedUnderPopup5984 extends JFrame {
+    static final CompletableFuture<RuntimeException> swingError = new CompletableFuture<>();
+
+    public static void main(String[] args) throws InterruptedException, InvocationTargetException, ExecutionException {
+        final ImWindowIsPlacedUnderPopup5984 frame;
+        {
+            final CompletableFuture<ImWindowIsPlacedUnderPopup5984> frameFuture = new CompletableFuture<>();
+            SwingUtilities.invokeAndWait(() -> {
+                try {
+                    final var result = new ImWindowIsPlacedUnderPopup5984();
+                    result.setVisible(true);
+                    frameFuture.complete(result);
+                } catch (Throwable err) {
+                    frameFuture.completeExceptionally(err);
+                }
+            });
+            frame = frameFuture.get();
+        }
+
+        try {
+            final var err = swingError.get();
+            if (err != null) {
+                throw err;
+            }
+        } finally {
+            if (frame != null) {
+                SwingUtilities.invokeAndWait(frame::dispose);
+            }
+        }
+    }
+
+
+    public ImWindowIsPlacedUnderPopup5984() {
+        super("JBR-5984");
+        setDefaultCloseOperation(HIDE_ON_CLOSE);
+
+        popupShowingButton = new JButton("Show a Popup");
+        add(popupShowingButton, BorderLayout.NORTH);
+
+        instructionTextArea = new JTextArea();
+        instructionTextArea.setLineWrap(true);
+        instructionTextArea.setWrapStyleWord(true);
+        instructionTextArea.setText(
+            """
+            INSTRUCTION:
+              1. Switch the input source to an input method (e.g. "Pinyin - Simplified");
+              2. Press the "Show a Popup" button;
+              3. Start typing into the text field on the shown popup;
+              4. Check if the input candidates' popup is shown above the java popup:
+                4.1. If it's shown above, press the "PASS" button;
+                4.2. Otherwise, press the "FAIL" button.
+            """
+        );
+        instructionTextArea.setEditable(false);
+        add(instructionTextArea, BorderLayout.CENTER);
+
+        final JPanel southContainer = new JPanel(new BorderLayout());
+        failTestButton = new JButton("FAIL");
+        passTestButton = new JButton("PASS");
+        southContainer.add(failTestButton, BorderLayout.LINE_START);
+        southContainer.add(passTestButton, BorderLayout.LINE_END);
+        add(southContainer, BorderLayout.SOUTH);
+
+        popupPanel = new JPanel();
+        popupTextField = new JTextArea();
+        popupTextField.setPreferredSize(new Dimension(200, 125));
+        popupPanel.add(popupTextField);
+
+        pack();
+        setSize(400, 250);
+        setLocationRelativeTo(null);
+
+        popup = new JPopupMenu();
+        popup.add(popupPanel);
+        popup.pack();
+
+        popupShowingButton.addActionListener(ignored -> popup.show(ImWindowIsPlacedUnderPopup5984.this, 100, 65));
+
+        failTestButton.addActionListener(ignored -> swingError.completeExceptionally(new RuntimeException("The tester has pressed FAILED")));
+        passTestButton.addActionListener(ignored -> swingError.complete(null));
+
+        addWindowListener(new WindowAdapter() {
+            @Override
+            public void windowClosing(WindowEvent e) {
+                swingError.completeExceptionally(new RuntimeException("The window was closed not through the \"PASS\"/\"FAIL\" buttons"));
+            }
+        });
+    }
+
+
+    private final JButton popupShowingButton;
+    private final JTextArea instructionTextArea;
+    private final JButton failTestButton;
+    private final JButton passTestButton;
+    private final JPanel popupPanel;
+    private final JTextArea popupTextField;
+    private final JPopupMenu popup;
+}