--- a/src/java.desktop/macosx/classes/sun/lwawt/macosx/CPlatformWindow.java	Mon Dec 17 14:19:06 2018 +0530
+++ b/src/java.desktop/macosx/classes/sun/lwawt/macosx/CPlatformWindow.java	Wed Dec 19 14:11:35 2018 -0800
@@ -266,12 +266,15 @@
         ComponentAccessor componentAccessor = AWTAccessor.getComponentAccessor();
         Object p1 = componentAccessor.getPeer(w1);
         Object p2 = componentAccessor.getPeer(w2);
-        if (p1 instanceof LWWindowPeer && p2 instanceof LWWindowPeer) {
-            return Long.compare(
-                    ((CPlatformWindow) (((LWWindowPeer) p1).getPlatformWindow())).lastBecomeMainTime,
-                    ((CPlatformWindow) (((LWWindowPeer) p2).getPlatformWindow())).lastBecomeMainTime);
+        long time1 = 0;
+        if (p1 instanceof LWWindowPeer) {
+            time1 = ((CPlatformWindow) (((LWWindowPeer) p1).getPlatformWindow())).lastBecomeMainTime;
         }
-        return 0;
+        long time2 = 0;
+        if (p2 instanceof LWWindowPeer) {
+            time2 = ((CPlatformWindow) (((LWWindowPeer) p2).getPlatformWindow())).lastBecomeMainTime;
+        }
+        return Long.compare(time1, time2);
     };
 
     // Bounds of the native widget but in the Java coordinate system.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/java/awt/Modal/MultipleDialogs/MixOfModalAndNonModalDialogs.java	Wed Dec 19 14:11:35 2018 -0800
@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. 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.
+ */
+
+import java.awt.Dialog;
+import java.awt.Frame;
+import java.util.concurrent.CountDownLatch;
+
+/**
+ * @test
+ * @key headful
+ * @bug 8215200
+ * @summary tests mixing of modal and non-modal dialogs
+ */
+public final class MixOfModalAndNonModalDialogs {
+
+    public static void main(final String[] args) throws Exception {
+        final Frame frame = new Frame();
+        try {
+            frame.setSize(300, 300);
+            frame.setLocationRelativeTo(null);
+            frame.setVisible(true);
+
+            // mix of modal, non-modal and invisible dialogs, all combinations
+            for (int step = 0; step < 3; ++step) {
+                for (int i = 0; i < 10; ++i) {
+                    showDialog(frame, i);
+                }
+                showModalDialog(frame);
+                for (int i = 0; i < 10; ++i) {
+                    showDialog(frame, i);
+                }
+            }
+        } finally {
+            frame.dispose();
+        }
+    }
+
+    private static void showDialog(final Frame frame, final int i) {
+        final  Dialog visible = new Dialog(frame);
+        visible.setLocationRelativeTo(null);
+        visible.setVisible(true);
+        if (i % 2 == 0) {
+            new Dialog(frame);
+        }
+    }
+
+    private static void showModalDialog(final Frame frame) throws Exception {
+        final CountDownLatch go = new CountDownLatch(1);
+        final Thread thread = new Thread(() -> {
+            final Dialog modal = new Dialog(frame, "Modal Dialog", true);
+            modal.pack();
+            go.countDown();
+            modal.setLocationRelativeTo(null);
+            modal.setVisible(true);
+        });
+        thread.start();
+        go.await();
+    }
+}