If you use the JFileChooser in SwingSet on Windows NT with JDK-1.2fcs-C it will throw the exceptions below and destroy the integrity of the entire app.

Steps to Reproduce:
0) Using the configuration above launch SwingSet.
1) Bring up the FileChooser.
2) Click on the 5 buttons on the top right of the window.
3) Click the Open button.
RESULT: The following exceptions are thrown, and the app becomes very difficult to use (odd repainting, slow mouse, etc.):
Exception occurred during event dispatching:
java.lang.IllegalMonitorStateException: current thread not owner
        at sun.awt.windows.WDialogPeer._show(Native Method)
        at sun.awt.windows.WDialogPeer.show(WDialogPeer.java:55)
        at java.awt.Dialog.show(Dialog.java:326)
        at com.sun.java.swing.JOptionPane.showOptionDialog(Compiled Code)
        at com.sun.java.swing.JOptionPane.showMessageDialog(JOptionPane.java:495)
        at com.sun.java.swing.JOptionPane.showMessageDialog(JOptionPane.java:475)
        at com.sun.java.swing.JOptionPane.showMessageDialog(JOptionPane.java:457)
        at SwingSet$9.actionPerformed(SwingSet.java:757)
        at com.sun.java.swing.AbstractButton.fireActionPerformed(Compiled Code)
        at com.sun.java.swing.AbstractButton$ForwardActionEvents.actionPerformed(AbstractButton.java:1051)
        at com.sun.java.swing.DefaultButtonModel.fireActionPerformed(Compiled Code)
        at com.sun.java.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:250)
        at com.sun.java.swing.AbstractButton.doClick(AbstractButton.java:206)
        at com.sun.java.swing.plaf.basic.BasicMenuItemUI$MenuDragMouseHandler.menuDragMouseReleased(BasicMenu
        at com.sun.java.swing.JMenuItem.fireMenuDragMouseReleased(Compiled Code)
        at com.sun.java.swing.JMenuItem.processMenuDragMouseEvent(Compiled Code)
        at com.sun.java.swing.JMenuItem.processMouseEvent(Compiled Code)
        at com.sun.java.swing.MenuSelectionManager.processMouseEvent(Compiled Code)
        at com.sun.java.swing.plaf.basic.BasicMenuUI$MouseInputHandler.mouseReleased(BasicMenuUI.java:245)
        at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:227)
        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.Component.dispatchEvent(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.Component.dispatchEvent(Compiled Code)
        at java.awt.EventQueue.dispatchEvent(Compiled Code)
        at java.awt.EventDispatchThread.run(Compiled Code)