java.lang.IllegalStateException: Illegal source modification with dirty model C:\Work Files\NetBeansProjects\WebApplication1\web\Page3.jsp
        at org.netbeans.modules.visualweb.insync.SourceUnit.setSourceDirty(SourceUnit.java:304)
        at org.netbeans.modules.visualweb.insync.SourceUnit.removeUpdate(SourceUnit.java:388)
        at org.netbeans.lib.editor.util.swing.PriorityDocumentListenerList.removeUpdate(PriorityDocumentListenerList.java:99)
        at javax.swing.text.AbstractDocument.fireRemoveUpdate(AbstractDocument.java:242)
        at org.netbeans.editor.BaseDocument.fireRemoveUpdate(BaseDocument.java:1617)
        at org.netbeans.editor.BaseDocumentEvent.undo(BaseDocumentEvent.java:310)
        at org.netbeans.editor.GuardedDocumentEvent.undo(GuardedDocumentEvent.java:69)
        at javax.swing.undo.CompoundEdit.undo(CompoundEdit.java:46)
        at org.netbeans.editor.BaseDocument$AtomicCompoundEdit.undo(BaseDocument.java:2167)
        at org.openide.text.CloneableEditorSupport$FilterUndoableEdit.undo(CloneableEditorSupport.java:2748)
        at org.openide.text.CloneableEditorSupport$BeforeModificationEdit.undo(CloneableEditorSupport.java:2908)
        at javax.swing.undo.UndoManager.undoTo(UndoManager.java:210)
        at javax.swing.undo.UndoManager.undo(UndoManager.java:275)
        at org.openide.text.CloneableEditorSupport$CESUndoRedoManager.access$2801(CloneableEditorSupport.java:2941)
        at org.openide.text.CloneableEditorSupport$CESUndoRedoManager$RenderUndo.run(CloneableEditorSupport.java:3102)
        at org.netbeans.editor.GuardedDocument.runAtomic(GuardedDocument.java:294)
        at org.openide.text.CloneableEditorSupport$CESUndoRedoManager$RenderUndo.<init>(CloneableEditorSupport.java:3082)
        at org.openide.text.CloneableEditorSupport$CESUndoRedoManager$RenderUndo.<init>(CloneableEditorSupport.java:3074)
        at org.openide.text.CloneableEditorSupport$CESUndoRedoManager.undo(CloneableEditorSupport.java:2974)
        at org.netbeans.core.multiview.MultiViewPeer$DelegateUndoRedo.undo(MultiViewPeer.java:773)
        at org.openide.actions.UndoAction.performAction(UndoAction.java:177)
        at org.openide.util.actions.CallableSystemAction$.run(CallableSystemAction.java:118)
        at org.netbeans.modules.openide.util.ActionsBridge.doPerformAction(ActionsBridge.java:77)
        at org.openide.util.actions.CallableSystemAction.actionPerformed(CallableSystemAction.java:114)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1849)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2169)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:420)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258)
        at javax.swing.AbstractButton.doClick(AbstractButton.java:302)
        at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:1051)
        at javax.swing.plaf.basic.BasicMenuItemUI$Handler.menuDragMouseReleased(BasicMenuItemUI.java:1155)
        at javax.swing.JMenuItem.fireMenuDragMouseReleased(JMenuItem.java:578)
        at javax.swing.JMenuItem.processMenuDragMouseEvent(JMenuItem.java:475)
        at javax.swing.JMenuItem.processMouseEvent(JMenuItem.java:422)
        at javax.swing.MenuSelectionManager.processMouseEvent(MenuSelectionManager.java:283)
        at javax.swing.plaf.basic.BasicPopupMenuUI$MouseGrabber.eventDispatched(BasicPopupMenuUI.java:783)
        at java.awt.Toolkit$SelectiveAWTEventListener.eventDispatched(Toolkit.java:2206)
        at java.awt.Toolkit$ToolkitEventMulticaster.eventDispatched(Toolkit.java:2100)
        at java.awt.Toolkit.notifyAWTEventListeners(Toolkit.java:2058)
        at java.awt.Component.dispatchEventImpl(Component.java:3883)
        at java.awt.Container.dispatchEventImpl(Container.java:2024)
        at java.awt.Component.dispatchEvent(Component.java:3819)
        at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4212)
        at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:3892)
        at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:3822)
        at java.awt.Container.dispatchEventImpl(Container.java:2010)
        at java.awt.Window.dispatchEventImpl(Window.java:1791)
        at java.awt.Component.dispatchEvent(Component.java:3819)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)