Debug: occasional exception thrown when stepping through debugger

[Brandon Pitman]

Does not seem to be caused by repeatable circumstances. Possibly a race condition? -- earlier testing showed some internal ops on JTable were multithreaded.

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at javax.swing.BufferStrategyPaintManager.flushAccumulatedRegion(BufferStrategyPaintManager.java:420)
    at javax.swing.BufferStrategyPaintManager.endPaint(BufferStrategyPaintManager.java:380)
    at javax.swing.RepaintManager.endPaint(RepaintManager.java:1270)
    at javax.swing.JComponent._paintImmediately(JComponent.java:5166)
    at javax.swing.JComponent.paintImmediately(JComponent.java:4971)
    at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:770)
    at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:728)
    at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:677)
    at javax.swing.RepaintManager.access$700(RepaintManager.java:59)
    at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1621)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:721)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:682)
    at java.awt.EventQueue$3.run(EventQueue.java:680)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:691)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:147)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:139)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:97)