WebNode quick guide: "Open in a new window" feature works only once (example 7)

Page: http://ipg-jets.us.oracle.com/JavaFX/id_common-files/id_common-outgoing/E17411_01/javafx/2.0/webview/jfxpub-webview.htm
"Open in a new window" feature works only once in example 7. If tried again, the following exception is thrown:
java.lang.IllegalArgumentException: Children: duplicate children added parent=HBox@1358f03[styleClass=browser-toolbar]
at javafx.scene.Parent$1.onProposedChange(Parent.java:325)
at com.sun.javafx.collections.VetoableObservableList.add(VetoableObservableList.java:145)
at com.sun.javafx.collections.ObservableListWrapper.add(ObservableListWrapper.java:90)
at Browser$4.call(Main.java:132)
at Browser$4.call(Main.java:129)
at com.sun.webpane.sg.UIClientImpl.createPage(UIClientImpl.java:43)
at com.sun.webpane.platform.WebPage.fwkCreateWindow(WebPage.java:1916)
at com.sun.webpane.platform.ContextMenu.twkHandleItemSelected(Native Method)
at com.sun.webpane.platform.ContextMenu.access$000(ContextMenu.java:6)
at com.sun.webpane.platform.ContextMenu$ShowContext.notifyItemSelected(ContextMenu.java:30)
at com.sun.webpane.sg.theme.ContextMenuImpl$1.handle(ContextMenuImpl.java:39)
at com.sun.webpane.sg.theme.ContextMenuImpl$1.handle(ContextMenuImpl.java:35)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:60)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:162)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:115)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:47)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:28)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.control.MenuItem.fire(MenuItem.java:366)
at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.doSelect(ContextMenuContent.java:1052)
at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer$6.handle(ContextMenuContent.java:1015)
at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer$6.handle(ContextMenuContent.java:1013)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:60)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:162)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:115)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:47)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.Scene$MouseHandler.process(Scene.java:2699)
at javafx.scene.Scene$MouseHandler.process(Scene.java:2520)
at javafx.scene.Scene$MouseHandler.access$1200(Scene.java:2493)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1226)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:1810)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:200)
at com.sun.glass.ui.View.handleMouseEvent(View.java:256)
at com.sun.glass.ui.View.notifyMouse(View.java:516)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:29)
at com.sun.glass.ui.win.WinApplication$2$1.run(WinApplication.java:62)
at java.lang.Thread.run(Thread.java:662)