src/share/classes/sun/awt/datatransfer/SunClipboard.java

@@ -259,10 +259,12 @@
             final AppContext disposedContext = (AppContext)evt.getSource();
             lostOwnershipLater(disposedContext);
         }
     }
 
+    public abstract void checkLostOwnership();
+
     protected void lostOwnershipImpl() {
         lostOwnershipLater(null);
     }
 
     /**