java.lang.Throwable: Locked by:
   at org.openide.filesystems.FileLock.<init>(FileLock.java:85)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.LockForFile.<init>(LockForFile.java:91)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.LockForFile.tryLock(LockForFile.java:102)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.FileObj.lock(FileObj.java:359)
   at org.openide.loaders.MultiDataObject$Entry.takeLock(MultiDataObject.java:1352)
   at org.netbeans.modules.openide.loaders.SimpleES$Environment.takeLock(SimpleES.java:188)
   at org.openide.text.DataEditorSupport$Env.markModified(DataEditorSupport.java:949)
   at org.openide.text.CloneableEditorSupport.notifyModified(CloneableEditorSupport.java:2001)
   at org.netbeans.modules.openide.loaders.SimpleES.notifyModified(SimpleES.java:123)
   at org.openide.text.CloneableEditorSupport.callNotifyModified(CloneableEditorSupport.java:1974)
   at org.openide.text.CloneableEditorSupport$Listener.vetoableChange(CloneableEditorSupport.java:2864)
   at org.netbeans.editor.BaseDocument.atomicLockImpl(BaseDocument.java:1648)
Caused: org.openide.filesystems.FileAlreadyLockedException: C:\Users\Mark\Documents\NetBeansProjects\JavaApplication18\src\javaapplication18\SupClass.java
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.LockForFile.registerLock(LockForFile.java:114)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.LockForFile.tryLock(LockForFile.java:103)
   at org.netbeans.modules.masterfs.filebasedfs.fileobjects.FileObj.lock(FileObj.java:359)
   at org.openide.filesystems.FileObject.delete(FileObject.java:379)
   at org.netbeans.modules.refactoring.java.plugins.ExtractSuperclassRefactoringPlugin$CreateSuperclassElement.undoChange(ExtractSuperclassRefactoringPlugin.java:388)
   at org.netbeans.modules.refactoring.api.RefactoringSession.undoRefactoring(RefactoringSession.java:208)
   at org.netbeans.modules.refactoring.spi.impl.UndoManager$SessionUndoItem.undo(UndoManager.java:385)
   at org.netbeans.modules.refactoring.spi.impl.UndoManager$1.run(UndoManager.java:194)
   at org.netbeans.modules.refactoring.spi.impl.UndoManager.undo(UndoManager.java:220)
   at org.netbeans.modules.refactoring.spi.impl.UndoableWrapper$UndoableEditDelegate.undo(UndoableWrapper.java:124)
   at org.openide.text.WrapUndoEdit.undo(WrapUndoEdit.java:93)
   at org.openide.awt.UndoRedo$Manager.undoTo(UndoRedo.java:230)
   at org.openide.awt.UndoRedo$Manager.undo(UndoRedo.java:200)
   at org.openide.text.UndoRedoManager.access$301(UndoRedoManager.java:98)
   at org.openide.text.UndoRedoManager$DocLockedRun.run(UndoRedoManager.java:645)
   at org.netbeans.editor.GuardedDocument.runAtomic(GuardedDocument.java:317)
   at org.openide.text.UndoRedoManager$DocLockedRun.<init>(UndoRedoManager.java:618)
   at org.openide.text.UndoRedoManager$DocLockedRun.<init>(UndoRedoManager.java:610)
   at org.openide.text.UndoRedoManager$DocLockedRun.<init>(UndoRedoManager.java:606)
   at org.openide.text.UndoRedoManager.undo(UndoRedoManager.java:434)
   at org.netbeans.core.multiview.MultiViewPeer$DelegateUndoRedo.undo(MultiViewPeer.java:813)
   at org.openide.actions.UndoRedoAction.actionPerformed(UndoRedoAction.java:224)
   at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
   at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
   at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
   at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
   at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
   at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:290)
   at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:289)
   at java.awt.Component.processMouseEvent(Component.java:6505)
   at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
   at java.awt.Component.processEvent(Component.java:6270)
   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.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4832)
   at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4492)
   at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4422)
   at java.awt.Container.dispatchEventImpl(Container.java:2273)
   at java.awt.Window.dispatchEventImpl(Window.java:2713)
   at java.awt.Component.dispatchEvent(Component.java:4687)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
   at java.awt.EventQueue.access$000(EventQueue.java:101)
   at java.awt.EventQueue$3.run(EventQueue.java:666)
   at java.awt.EventQueue$3.run(EventQueue.java:664)
   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:680)
   at java.awt.EventQueue$4.run(EventQueue.java:678)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:158)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)