java.lang.NullPointerException
	at java.awt.Component.requestFocusHelper(Component.java:6535)
	at java.awt.Component.requestFocus(Component.java:6370)
	at javax.swing.JComponent.requestFocus(JComponent.java:1416)
	at org.netbeans.core.windows.view.ViewHierarchy.updateDesktop(ViewHierarchy.java:673)
	at org.netbeans.core.windows.view.DefaultView.changeGUI(DefaultView.java:329)
	at org.netbeans.core.windows.ViewRequestor.dispatchRequest(ViewRequestor.java:238)
	at org.netbeans.core.windows.ViewRequestor.processRequest(ViewRequestor.java:214)
	at org.netbeans.core.windows.ViewRequestor.postRequest(ViewRequestor.java:152)
	at org.netbeans.core.windows.ViewRequestor.scheduleRequest(ViewRequestor.java:91)
	at org.netbeans.core.windows.Central.addModeClosedTopComponent(Central.java:635)
	at org.netbeans.core.windows.Central.userClosedTopComponent(Central.java:1533)
	at org.netbeans.core.windows.view.DefaultView.userClosedTopComponent(DefaultView.java:724)
	at org.netbeans.core.windows.view.ui.TabbedHandler.actionPerformed(TabbedHandler.java:292)
	at org.netbeans.swing.tabcontrol.TabbedContainer.postActionEvent(TabbedContainer.java:662)
	at org.netbeans.swing.tabcontrol.TabbedContainerUI.shouldPerformAction(TabbedContainerUI.java:134)
	at org.netbeans.swing.tabcontrol.plaf.DefaultTabbedContainerUI.access$2600(DefaultTabbedContainerUI.java:80)
	at org.netbeans.swing.tabcontrol.plaf.DefaultTabbedContainerUI$DisplayerActionListener.actionPerformed(DefaultTabbedContainerUI.java:1229)
	at org.netbeans.swing.tabcontrol.TabDisplayer.postActionEvent(TabDisplayer.java:513)
	at org.netbeans.swing.tabcontrol.TabDisplayerUI.shouldPerformAction(TabDisplayerUI.java:144)
	at org.netbeans.swing.tabcontrol.plaf.BasicTabDisplayerUI.access$1500(BasicTabDisplayerUI.java:74)
	at org.netbeans.swing.tabcontrol.plaf.BasicTabDisplayerUI$BasicDisplayerMouseListener.performCommand(BasicTabDisplayerUI.java:689)
	at org.netbeans.swing.tabcontrol.plaf.BasicTabDisplayerUI$BasicDisplayerMouseListener.potentialCommand(BasicTabDisplayerUI.java:674)
	at org.netbeans.swing.tabcontrol.plaf.BasicTabDisplayerUI$BasicDisplayerMouseListener.mouseReleased(BasicTabDisplayerUI.java:722)
	at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:231)
	at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:231)
	at java.awt.Component.processMouseEvent(Component.java:5488)
	at javax.swing.JComponent.processMouseEvent(JComponent.java:3126)
	at java.awt.Component.processEvent(Component.java:5253)
	at java.awt.Container.processEvent(Container.java:1966)
	at java.awt.Component.dispatchEventImpl(Component.java:3955)
	at java.awt.Container.dispatchEventImpl(Container.java:2024)
	at java.awt.Component.dispatchEvent(Component.java:3803)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4212)
	at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3892)
	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3822)
	at java.awt.Container.dispatchEventImpl(Container.java:2010)
	at java.awt.Window.dispatchEventImpl(Window.java:1774)
	at java.awt.Component.dispatchEvent(Component.java:3803)
[catch] at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
	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)

----------

Following exception is poping up:

java.lang.NullPointerException
	at java.awt.Component.requestFocusHelper(Component.java:6535)
	at java.awt.Component.requestFocusInWindow(Component.java:6468)
	at javax.swing.JComponent.requestFocusInWindow(JComponent.java:1466)
	at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:339)
	at java.awt.Component.dispatchEventImpl(Component.java:3841)
	at java.awt.Container.dispatchEventImpl(Container.java:2024)
	at java.awt.Window.dispatchEventImpl(Window.java:1774)
	at java.awt.Component.dispatchEvent(Component.java:3803)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
[catch] at java.awt.SequencedEvent.dispatch(SequencedEvent.java:93)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
	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)