# HG changeset patch
# User serb
# Date 1541904515 28800
#      Sat Nov 10 18:48:35 2018 -0800
# Node ID 271dc91c6378b9ceb7eea01e789c9b569befae86
# Parent  f0b93fbd8cf8b89d9d20a5314065154912b3dd36
8211435: Exception in thread "AWT-EventQueue-1" java.lang.IllegalArgumentException: null source
Reviewed-by: dmarkov, lbourges, kaddepalli, prr

diff --git a/src/share/classes/java/awt/DefaultKeyboardFocusManager.java b/src/share/classes/java/awt/DefaultKeyboardFocusManager.java
--- a/src/share/classes/java/awt/DefaultKeyboardFocusManager.java
+++ b/src/share/classes/java/awt/DefaultKeyboardFocusManager.java
@@ -30,18 +30,17 @@
 import java.awt.peer.ComponentPeer;
 import java.awt.peer.LightweightPeer;
 import java.lang.ref.WeakReference;
+import java.util.Iterator;
 import java.util.LinkedList;
-import java.util.Iterator;
 import java.util.ListIterator;
 import java.util.Set;
 
-import sun.util.logging.PlatformLogger;
-
+import sun.awt.AWTAccessor;
 import sun.awt.AppContext;
+import sun.awt.CausedFocusEvent;
 import sun.awt.SunToolkit;
-import sun.awt.AWTAccessor;
-import sun.awt.CausedFocusEvent;
 import sun.awt.TimedWindowEvent;
+import sun.util.logging.PlatformLogger;
 
 /**
  * The default KeyboardFocusManager for AWT applications. Focus traversal is
@@ -777,7 +776,7 @@
                     : NULL_WINDOW_WR;
                 typeAheadAssertions(currentFocusedWindow, we);
 
-                if (oppositeWindow == null) {
+                if (oppositeWindow == null && activeWindow != null) {
                     // Then we need to deactive the active Window as well.
                     // No need to synthesize in other cases, because
                     // WINDOW_ACTIVATED will handle it if necessary.
diff --git a/test/java/awt/Focus/NullActiveWindowOnFocusLost/NullActiveWindowOnFocusLost.java b/test/java/awt/Focus/NullActiveWindowOnFocusLost/NullActiveWindowOnFocusLost.java
new file mode 100644
--- /dev/null
+++ b/test/java/awt/Focus/NullActiveWindowOnFocusLost/NullActiveWindowOnFocusLost.java
@@ -0,0 +1,82 @@
+/*
+ * 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.Button;
+import java.awt.Frame;
+import java.util.concurrent.TimeUnit;
+
+import sun.awt.SunToolkit;
+
+/**
+ * @test
+ * @bug 8211435
+ * @modules java.desktop/sun.awt
+ */
+public final class NullActiveWindowOnFocusLost {
+
+    private static volatile long endtime;
+    private static Throwable failed;
+
+    public static void main(final String[] args) throws Exception {
+        // Will run the test no more than 30 seconds
+        endtime = System.nanoTime() + TimeUnit.SECONDS.toNanos(30);
+        Thread.setDefaultUncaughtExceptionHandler((t, e) -> failed = e);
+
+        final Thread[] threads = new Thread[20];
+        for (int i = 0; i < threads.length; i++) {
+            threads[i] = testThread(i);
+        }
+        for (final Thread thread : threads) {
+            thread.start();
+        }
+        for (final Thread thread : threads) {
+            thread.join();
+        }
+        if (failed != null) {
+            failed.printStackTrace();
+            throw new RuntimeException(failed);
+        }
+    }
+
+    private static Thread testThread(int index) {
+        return new Thread(new ThreadGroup("TG " + index), () -> {
+            SunToolkit.createNewAppContext();
+            while (!isComplete()) {
+                final Frame frame = new Frame();
+                frame.setSize(300, 300);
+                frame.add(new Button("Button"));
+                frame.setLocationRelativeTo(null);
+                frame.setVisible(true);
+                try {
+                    Thread.sleep(index); // increase probability of the failure
+                } catch (InterruptedException ignored) {
+                }
+                frame.dispose();
+            }
+        });
+    }
+
+    private static boolean isComplete() {
+        return endtime - System.nanoTime() < 0 || failed != null;
+    }
+}