4966168 reported that JInternalFrames are not serializable in Motif and GTK L&F. The fix to that bug did not resolve the issue with GTK L&F. An exception is still thrown.

Steps to reproduce:
1) Run the attached test TestSerializeInternalFrame
2) Change L&F to GTK using Menu "Look And Feel"
3) Click on button "Serialize InternalFrame"
4) It will throw Exception in console
5) Now try serializing in some other look and feel it will
   give message ""Successfully serialized JInternalFrame" on console

Tested on Tiger b39

Following is the exception message when serializing JInternalFrame under GTK
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java.io.NotSerializableException: javax.swing.plaf.basic.BasicInternalFrameUI$Handler
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1072)
at java.io.ObjectOutputStream.access+100(ObjectOutputStream.java:135)
at java.io.ObjectOutputStream$PutFieldImpl.writeFields(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeFields(ObjectOutputStream.java:418)
at java.awt.Container.writeObject(Container.java:3452)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:494)
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:890)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1330)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1281)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1070)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:291)
at TestSerializeInternalFrame$1.actionPerformed(TestSerializeInternalFrame.java:24)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1834)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2152)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:420)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:234)
at java.awt.Component.processMouseEvent(Component.java:5465)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3078)
at java.awt.Component.processEvent(Component.java:5230)
at java.awt.Container.processEvent(Container.java:1961)
at java.awt.Component.dispatchEventImpl(Component.java:3933)
at java.awt.Container.dispatchEventImpl(Container.java:2019)
at java.awt.Component.dispatchEvent(Component.java:3781)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4203)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3883)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3813)
at java.awt.Container.dispatchEventImpl(Container.java:2005)
at java.awt.Window.dispatchEventImpl(Window.java:1757)
at java.awt.Component.dispatchEvent(Component.java:3781)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:234)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)