javax.swing.undo.CannotUndoException
   at org.netbeans.editor.BaseDocumentEvent.undo(BaseDocumentEvent.java:268)
   at org.netbeans.editor.GuardedDocumentEvent.undo(GuardedDocumentEvent.java:72)
   at org.netbeans.modules.editor.lib2.document.StableCompoundEdit.undo(StableCompoundEdit.java:93)
   at org.netbeans.editor.BaseDocument$AtomicCompoundEdit.undo(BaseDocument.java:2196)
   at org.netbeans.editor.BaseDocument.undoAtomicEdits(BaseDocument.java:2114)
   at org.netbeans.editor.BaseDocument.breakAtomicLock(BaseDocument.java:1800)
   at org.netbeans.editor.GuardedDocument.runAtomicAsUser(GuardedDocument.java:357)
   at org.netbeans.editor.BaseKit$InsertBreakAction.actionPerformed(BaseKit.java:1339)
   at org.netbeans.editor.BaseAction.actionPerformed(BaseAction.java:339)
   at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1664)
   at javax.swing.JComponent.processKeyBinding(JComponent.java:2879)
   at javax.swing.JComponent.processKeyBindings(JComponent.java:2926)
   at javax.swing.JComponent.processKeyEvent(JComponent.java:2842)
   at java.awt.Component.processEvent(Component.java:6282)
   at java.awt.Container.processEvent(Container.java:2229)
   at java.awt.Component.dispatchEventImpl(Component.java:4861)
   at java.awt.Container.dispatchEventImpl(Container.java:2287)
   at java.awt.Component.dispatchEvent(Component.java:4687)
   at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1895)
   at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:762)
   at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1027)
   at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:899)
   at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:727)
   at java.awt.Component.dispatchEventImpl(Component.java:4731)
   at java.awt.Container.dispatchEventImpl(Container.java:2287)
   at java.awt.Window.dispatchEventImpl(Window.java:2719)
   at java.awt.Component.dispatchEvent(Component.java:4687)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:729)
   at java.awt.EventQueue.access$200(EventQueue.java:103)
   at java.awt.EventQueue$3.run(EventQueue.java:688)
   at java.awt.EventQueue$3.run(EventQueue.java:686)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
   at java.awt.EventQueue$4.run(EventQueue.java:702)
   at java.awt.EventQueue$4.run(EventQueue.java:700)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:699)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:159)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)