Every once in a while, when I try to close the schema file, I get an exception [1]. It does not seem to be affecting
anything, but exposing an NPE is a bad thing..

[1] java.lang.NullPointerException
    at org.openide.explorer.ExplorerManager.findExplorerActionsImpl(ExplorerManager.java:829)
    at org.openide.explorer.ExplorerUtils.activateActions(ExplorerUtils.java:194)
    at
org.netbeans.modules.xml.schema.multiview.SchemaColumnViewMultiViewElement.componentDeactivated(SchemaColumnViewMultiViewElement.java:411)
    at org.netbeans.core.multiview.MultiViewPeer.peerComponentDeactivated(MultiViewPeer.java:220)
    at
org.netbeans.core.multiview.MultiViewCloneableTopComponent.componentDeactivated(MultiViewCloneableTopComponent.java:129)
    at org.openide.windows.WindowManager.activateComponent(WindowManager.java:270)
Caused: java.lang.IllegalStateException: [Winsys] TopComponent
org.netbeans.core.multiview.MultiViewCloneableTopComponent throws runtime exception from its componentDeactivated() method.
Please repair it! Probable cause is at
org.openide.explorer.ExplorerManager.findExplorerActionsImpl(ExplorerManager.java:829)
    at org.openide.windows.WindowManager.logThrowable(WindowManager.java:361)
    at org.openide.windows.WindowManager.activateComponent(WindowManager.java:272)
    at org.openide.windows.WindowManager.componentCloseNotify(WindowManager.java:320)
    at org.netbeans.core.windows.WindowManagerImpl.notifyTopComponentClosed(WindowManagerImpl.java:981)
    at org.netbeans.core.windows.Central.removeModeTopComponent(Central.java:959)
    at org.netbeans.core.windows.Central.userClosedTopComponent(Central.java:1929)
    at org.netbeans.core.windows.view.DefaultView.userClosedTopComponent(DefaultView.java:741)
    at org.netbeans.core.windows.view.ui.TabbedHandler.actionPerformed(TabbedHandler.java:319)
    at org.netbeans.swing.tabcontrol.TabbedContainer.postActionEvent(TabbedContainer.java:680)
    at org.netbeans.swing.tabcontrol.TabbedContainerUI.shouldPerformAction(TabbedContainerUI.java:162)
    at org.netbeans.swing.tabcontrol.plaf.DefaultTabbedContainerUI.access$2700(DefaultTabbedContainerUI.java:109)
    at
org.netbeans.swing.tabcontrol.plaf.DefaultTabbedContainerUI$DisplayerActionListener.actionPerformed(DefaultTabbedContainerUI.java:1258)
    at org.netbeans.swing.tabcontrol.TabDisplayer.postActionEvent(TabDisplayer.java:543)
    at org.netbeans.swing.tabcontrol.TabDisplayerUI.shouldPerformAction(TabDisplayerUI.java:176)
    at org.netbeans.swing.tabcontrol.plaf.BasicTabDisplayerUI.access$1500(BasicTabDisplayerUI.java:116)
    at
org.netbeans.swing.tabcontrol.plaf.BasicTabDisplayerUI$BasicDisplayerMouseListener.performCommand(BasicTabDisplayerUI.java:715)
    at
org.netbeans.swing.tabcontrol.plaf.BasicTabDisplayerUI$BasicDisplayerMouseListener.potentialCommand(BasicTabDisplayerUI.java:700)
    at
org.netbeans.swing.tabcontrol.plaf.BasicTabDisplayerUI$BasicDisplayerMouseListener.mouseReleased(BasicTabDisplayerUI.java:748)
    at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:231)
    at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:231)
    at java.awt.Component.processMouseEvent(Component.java:5583)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3135)
    at java.awt.Component.processEvent(Component.java:5348)
    at java.awt.Container.processEvent(Container.java:2010)
    at java.awt.Component.dispatchEventImpl(Component.java:4050)
    at java.awt.Container.dispatchEventImpl(Container.java:2068)
    at java.awt.Component.dispatchEvent(Component.java:3885)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4256)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3936)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3866)
    at java.awt.Container.dispatchEventImpl(Container.java:2054)
    at java.awt.Window.dispatchEventImpl(Window.java:1791)
    at java.awt.Component.dispatchEvent(Component.java:3885)
[catch] at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
    at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
    at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:269)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:184)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:176)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)