src/macosx/native/sun/awt/AWTWindow.m

*** 1129,1147 ****
   */
  JNIEXPORT jobject
  JNICALL Java_sun_lwawt_macosx_CPlatformWindow_nativeGetTopmostPlatformWindowUnderMouse
  (JNIEnv *env, jclass clazz)
  {
!     jobject topmostWindowUnderMouse = nil;
  
      JNF_COCOA_ENTER(env);
-     AWT_ASSERT_APPKIT_THREAD;
  
      AWTWindow *awtWindow = [AWTWindow getTopmostWindowUnderMouse];
      if (awtWindow != nil) {
          topmostWindowUnderMouse = [awtWindow.javaPlatformWindow jObject];
      }
  
      JNF_COCOA_EXIT(env);
  
      return topmostWindowUnderMouse;
  }
--- 1129,1148 ----
   */
  JNIEXPORT jobject
  JNICALL Java_sun_lwawt_macosx_CPlatformWindow_nativeGetTopmostPlatformWindowUnderMouse
  (JNIEnv *env, jclass clazz)
  {
!     __block jobject topmostWindowUnderMouse = nil;
  
      JNF_COCOA_ENTER(env);
  
+     [ThreadUtilities performOnMainThreadWaiting:YES block:^{
          AWTWindow *awtWindow = [AWTWindow getTopmostWindowUnderMouse];
          if (awtWindow != nil) {
              topmostWindowUnderMouse = [awtWindow.javaPlatformWindow jObject];
          }
+     }];
  
      JNF_COCOA_EXIT(env);
  
      return topmostWindowUnderMouse;
  }