java.lang.ClassCastException
        at javax.swing.LayoutComparator.compare(LayoutComparator.java:72)
        at javax.swing.DefaultFocusManager.compareTabOrder(DefaultFocusManager.java:130)
        at javax.swing.CompareTabOrderComparator.compare(CompareTabOrderComparator.java:153)
        at java.util.Arrays.mergeSort(Arrays.java:1270)
        at java.util.Arrays.mergeSort(Arrays.java:1281)
        at java.util.Arrays.mergeSort(Arrays.java:1282)
        at java.util.Arrays.mergeSort(Arrays.java:1282)
        at java.util.Arrays.sort(Arrays.java:1210)
        at java.util.Collections.sort(Collections.java:159)
        at javax.swing.SortingFocusTraversalPolicy.enumerateAndSortCycle(SortingFocusTraversalPolicy.java:119)
        at javax.swing.SortingFocusTraversalPolicy.getFirstComponent(SortingFocusTraversalPolicy.java:434)
        at javax.swing.LayoutFocusTraversalPolicy.getFirstComponent(LayoutFocusTraversalPolicy.java:148)
        at javax.swing.DefaultFocusManager.getFirstComponent(DefaultFocusManager.java:103)
        at javax.swing.LegacyGlueFocusTraversalPolicy.getFirstComponent(LegacyGlueFocusTraversalPolicy.java:115)
        at javax.swing.LegacyGlueFocusTraversalPolicy.getDefaultComponent(LegacyGlueFocusTraversalPolicy.java:133)
        at java.awt.FocusTraversalPolicy.getInitialComponent(FocusTraversalPolicy.java:152)
        at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:340)
        at java.awt.Component.dispatchEventImpl(Component.java:4502)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Window.dispatchEventImpl(Window.java:2475)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.SequencedEvent.dispatch(SequencedEvent.java:101)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)