SwingSet InternalFrame creator throws exception on Windows with JDK-1.2beta4-I with the windows look and feel only. This also occurred with JDK-1.2beta4-H.

Steps to Reproduce:
0) Run SwingSet on Windows NT with the above configuration.
1) Go to the InternalFrame pane.
2) Switch to windows look and feel.
3) Start creating frames. Make at least 7 of them.
4) Turn features on and off with check boxes.
5) Click the clear button.
6) Move the frame creator window.
7) Keep repeating the above in different combinations.
RESULT: Eventually the following exceptions will be thrown:
Exception occurred during event dispatching:
java.lang.NullPointerException
        at com.sun.java.swing.plaf.basic.BasicInternalFrameUI.deactivateFrame(Compiled Code)
        at com.sun.java.swing.plaf.basic.BasicInternalFrameUI$InternalFramePropertyChangeListener.propertyChan
        at com.sun.java.swing.event.SwingPropertyChangeSupport.firePropertyChange(Compiled Code)
        at com.sun.java.swing.JComponent.firePropertyChange(Compiled Code)
        at com.sun.java.swing.JInternalFrame.setSelected(Compiled Code)
        at com.sun.java.swing.plaf.windows.WindowsDesktopManager.activateFrame(Compiled Code)
        at com.sun.java.swing.plaf.basic.BasicInternalFrameUI.activateFrame(Compiled Code)
        at com.sun.java.swing.plaf.basic.BasicInternalFrameUI$InternalFramePropertyChangeListener.propertyChan
        at com.sun.java.swing.event.SwingPropertyChangeSupport.firePropertyChange(Compiled Code)
        at com.sun.java.swing.JComponent.firePropertyChange(Compiled Code)
        at com.sun.java.swing.JInternalFrame.setSelected(Compiled Code)
        at InternalWindowPanel.actionPerformed(Compiled Code)
        at com.sun.java.swing.AbstractButton.fireActionPerformed(Compiled Code)
        at com.sun.java.swing.AbstractButton$ForwardActionEvents.actionPerformed(Compiled Code)
        at com.sun.java.swing.DefaultButtonModel.fireActionPerformed(Compiled Code)
        at com.sun.java.swing.DefaultButtonModel.setPressed(Compiled Code)
        at com.sun.java.swing.plaf.basic.BasicButtonListener.mouseReleased(Compiled Code)
        at java.awt.Component.processMouseEvent(Compiled Code)
        at java.awt.Component.processEvent(Compiled Code)
        at java.awt.Container.processEvent(Compiled Code)
        at java.awt.Component.dispatchEventImpl(Compiled Code)
        at java.awt.Container.dispatchEventImpl(Compiled Code)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Compiled Code)
        at java.awt.LightweightDispatcher.processMouseEvent(Compiled Code)
        at java.awt.LightweightDispatcher.dispatchEvent(Compiled Code)
        at java.awt.Container.dispatchEventImpl(Compiled Code)
        at java.awt.Window.dispatchEventImpl(Compiled Code)
        at java.awt.EventQueue.dispatchEvent(Compiled Code)
        at java.awt.EventDispatchThread.run(Compiled Code)