src/share/classes/sun/awt/SunToolkit.java

@@ -575,11 +575,14 @@
      * Execute a chunk of code on the Java event handler thread for the
      * given target.  Does not wait for the execution to occur before
      * returning to the caller.
      */
     public static void executeOnEventHandlerThread(PeerEvent peerEvent) {
-        postEvent(targetToAppContext(peerEvent.getSource()), peerEvent);
+        AppContext appContext = targetToAppContext(peerEvent.getSource());
+        if (appContext != null) {
+            postEvent(appContext, peerEvent);
+        }
     }
 
     /*
      * Execute a chunk of code on the Java event handler thread. The
      * method takes into account provided AppContext and sets

@@ -632,10 +635,13 @@
      * Use this call to ensure that a given task is being executed
      * (or not being) on the event dispatch thread for the given target.
      */
     public static boolean isDispatchThreadForAppContext(Object target) {
         AppContext appContext = targetToAppContext(target);
+        if (appContext == null) {
+            return false;
+        }
         EventQueue eq = (EventQueue)appContext.get(AppContext.EVENT_QUEUE_KEY);
 
         AWTAccessor.EventQueueAccessor accessor = AWTAccessor.getEventQueueAccessor();
         return accessor.isDispatchThreadImpl(eq);
     }