Application in browse cann't exit using FX.exit()

In the test of Marina b10, we run a application "FXAddressBook" from sample projects.
After the application was launched successfully, I clicked the exit button to exit, but it had no response.
And then I clicked the exit button again, a exception came out in NB output:

Exception in thread "AWT-EventQueue-4" java.lang.IllegalStateException: Can not call FX.exit() twice
at javafx.lang.FX.exit(FX.java:188)
at fxaddressbook.Footer$1.lambda(Footer.fx:69)
at fxaddressbook.Footer$1.invoke(Footer.fx:68)
at fxaddressbook.Footer$1.invoke(Footer.fx:68)
at javafx.scene.Node.impl_processMouseEvent(Node.fx:1911)
at javafx.scene.Node.preprocessMouseEvent(Node.fx:1935)
at javafx.scene.Scene$MouseHandler.process(Scene.fx:665)
at javafx.scene.Scene$MouseHandler.process(Scene.fx:550)
at javafx.scene.Scene.impl_processMouseEvent(Scene.fx:368)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.fx:496)
at com.sun.javafx.tk.swing.SwingScene$SwingScenePanel.doMouseEvent(SwingScene.java:385)
at com.sun.javafx.tk.swing.SwingScene$SwingScenePanel.mouseClicked(SwingScene.java:389)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at com.sun.embeddedswing.EmbeddedEventQueue.dispatchEvent(EmbeddedEventQueue.java:440)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

BTW, this problem only happens with browser execution.

#step to reproduce.
 1. load http://jfxsamples.sfbay.sun.com/ ,
 2. click "FXAddress"to launch the aplication.
 3. click exit button more than one time