java.lang.NullPointerException
   at java.awt.Component$NativeInLightFixer.removeReferences(Component.java:8863)
   at java.awt.Component$NativeInLightFixer.componentRemoved(Component.java:8839)
   at java.awt.Container.processContainerEvent(Container.java:2068)
   at java.awt.Container.processEvent(Container.java:2036)
   at java.awt.Component.dispatchEventImpl(Component.java:4653)
   at java.awt.Container.dispatchEventImpl(Container.java:2097)
   at java.awt.Component.dispatchEvent(Component.java:4481)
   at java.awt.Container.remove(Container.java:1160)
   at javax.swing.JLayeredPane.remove(JLayeredPane.java:227)
   at java.awt.Container.remove(Container.java:1196)
   at javax.swing.PopupFactory$ContainerPopup.hide(PopupFactory.java:483)
   at javax.swing.PopupFactory$MediumWeightPopup.hide(PopupFactory.java:862)
   at org.openide.explorer.view.ViewTooltips.ensureOldPopupsHidden(ViewTooltips.java:300)
   at org.openide.explorer.view.ViewTooltips.showJTree(ViewTooltips.java:260)
   at org.openide.explorer.view.ViewTooltips.show(ViewTooltips.java:192)
   at org.openide.explorer.view.ViewTooltips.mouseMoved(ViewTooltips.java:166)
   at java.awt.AWTEventMulticaster.mouseMoved(AWTEventMulticaster.java:313)
   at java.awt.AWTEventMulticaster.mouseMoved(AWTEventMulticaster.java:312)
   at java.awt.Component.processMouseMotionEvent(Component.java:6335)
   at javax.swing.JComponent.processMouseMotionEvent(JComponent.java:3285)
   at java.awt.Component.processEvent(Component.java:6059)
   at java.awt.Container.processEvent(Container.java:2039)
   at java.awt.Component.dispatchEventImpl(Component.java:4653)
   at java.awt.Container.dispatchEventImpl(Container.java:2097)
   at java.awt.Component.dispatchEvent(Component.java:4481)
   at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4575)
   at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4249)
   at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4166)
   at java.awt.Container.dispatchEventImpl(Container.java:2083)
   at java.awt.Window.dispatchEventImpl(Window.java:2482)
   at java.awt.Component.dispatchEvent(Component.java:4481)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:648)
   at java.awt.EventQueue.access$000(EventQueue.java:84)
   at java.awt.EventQueue$1.run(EventQueue.java:607)
   at java.awt.EventQueue$1.run(EventQueue.java:605)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
   at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
   at java.awt.EventQueue$2.run(EventQueue.java:621)
   at java.awt.EventQueue$2.run(EventQueue.java:619)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:618)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:158)
   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)