javax.swing.undo.CannotUndoException
   at org.netbeans.editor.BaseDocument.breakAtomicLock(BaseDocument.java:1873)
   at org.netbeans.editor.GuardedDocument.runAtomic(GuardedDocument.java:320)
   at org.openide.text.NbDocument.runAtomic(NbDocument.java:422)
   at org.openide.text.CloneableEditorSupport.reloadDocument(CloneableEditorSupport.java:1682)
   at org.netbeans.modules.properties.PropertiesEditorSupport.reloadDocument(PropertiesEditorSupport.java:378)
   at org.openide.text.CloneableEditorSupport.checkReload(CloneableEditorSupport.java:2316)
   at org.openide.text.CloneableEditorSupport.access$2600(CloneableEditorSupport.java:133)
   at org.openide.text.CloneableEditorSupport$Listener$1.run(CloneableEditorSupport.java:2952)
   at org.netbeans.editor.GuardedDocument.runAtomic(GuardedDocument.java:314)
   at org.openide.text.NbDocument.runAtomic(NbDocument.java:422)
   at org.openide.text.CloneableEditorSupport$Listener$1.run(CloneableEditorSupport.java:2944)
   at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:148)
   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)