--- old/src/share/classes/sun/swing/JLightweightFrame.java	2013-09-03 14:47:20.000000000 +0400
+++ new/src/share/classes/sun/swing/JLightweightFrame.java	2013-09-03 14:47:20.000000000 +0400
@@ -237,6 +237,7 @@
                 return true;
             }
         };
+        contentPane.setOpaque(false);
         contentPane.setLayout(new BorderLayout());
         contentPane.add(component);
         setContentPane(contentPane);