--- /dev/null	2017-05-19 18:25:14.000000000 -0700
+++ new/test/javax/imageio/AppContextTest.java	2017-05-19 18:25:14.000000000 -0700
@@ -0,0 +1,141 @@
+/*
+ * Copyright (c) 2001, 2017, 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.
+ */
+
+/*
+ * @test
+ * @bug 4421190
+ * @summary Tests that Image I/O statics may be referenced properly from
+ *          multiple AppContexts, as would be the case for multiple Applets in a
+ *          single VM. Each AppContext should get its own copy of the registry
+ *          and the caching parameters in the ImageIO class.
+ * @modules java.desktop/sun.awt
+ */
+
+import java.io.File;
+import java.io.IOException;
+
+import javax.imageio.ImageIO;
+import javax.imageio.spi.IIORegistry;
+
+import sun.awt.SunToolkit;
+
+class TestThread extends Thread {
+
+    IIORegistry registry;
+    boolean useCache;
+    File cacheDirectory;
+    boolean cacheSettingsOK = false;
+    String threadName;
+
+    boolean gotCrosstalk = false;
+
+    public TestThread(ThreadGroup tg,
+                      boolean useCache, File cacheDirectory,
+                      String threadName) {
+        super(tg, threadName);
+        this.useCache = useCache;
+        this.cacheDirectory = cacheDirectory;
+        this.threadName = threadName;
+    }
+
+    public void run() {
+//          System.out.println("Thread " + threadName + " in thread group " +
+//                             getThreadGroup().getName());
+
+        // Create a new AppContext as though we were an applet
+        SunToolkit.createNewAppContext();
+
+        // Get default registry and store reference
+        this.registry = IIORegistry.getDefaultInstance();
+
+        for (int i = 0; i < 10; i++) {
+//              System.out.println(threadName +
+//                                 ": setting cache parameters to " +
+//                                 useCache + ", " + cacheDirectory);
+            ImageIO.setUseCache(useCache);
+            ImageIO.setCacheDirectory(cacheDirectory);
+
+            try {
+                sleep(1000L);
+            } catch (InterruptedException e) {
+            }
+
+//              System.out.println(threadName + ": reading cache parameters");
+            boolean newUseCache = ImageIO.getUseCache();
+            File newCacheDirectory = ImageIO.getCacheDirectory();
+            if (newUseCache != useCache ||
+                newCacheDirectory != cacheDirectory) {
+//                  System.out.println(threadName + ": got " +
+//                                     newUseCache + ", " +
+//                                     newCacheDirectory);
+//                  System.out.println(threadName + ": crosstalk encountered!");
+                gotCrosstalk = true;
+            }
+        }
+    }
+
+    public IIORegistry getRegistry() {
+        return registry;
+    }
+
+    public boolean gotCrosstalk() {
+        return gotCrosstalk;
+    }
+}
+
+public class AppContextTest {
+
+    public AppContextTest() {
+        ThreadGroup tg0 = new ThreadGroup("ThreadGroup0");
+        ThreadGroup tg1 = new ThreadGroup("ThreadGroup1");
+
+        TestThread t0 =
+            new TestThread(tg0, false, null, "TestThread 0");
+        TestThread t1 =
+            new TestThread(tg1, true, new File("."), "TestThread 1");
+
+        t0.start();
+        t1.start();
+
+        try {
+            t0.join();
+        } catch (InterruptedException ie0) {
+        }
+        try {
+            t1.join();
+        } catch (InterruptedException ie1) {
+        }
+
+        if (t0.gotCrosstalk() || t1.gotCrosstalk()) {
+            throw new RuntimeException("ImageIO methods had crosstalk!");
+        }
+
+        if (t0.getRegistry() == t1.getRegistry()) {
+            throw new RuntimeException("ThreadGroups had same IIORegistry!");
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        new AppContextTest();
+    }
+}