从Exception追踪系统弹出菜单的调用关系：
E/AndroidRuntime( 456): java.lang.NullPointerException
E/AndroidRuntime( 456): at com.android.internal.view.menu.IconMenuView.addItemViewWithPos(IconMenuView.java:443)
E/AndroidRuntime( 456): at com.android.internal.view.menu.IconMenuView.updateChildren(IconMenuView.java:506)
E/AndroidRuntime( 456): at com.android.internal.view.menu.IconMenuView.initialize(IconMenuView.java:487)
E/AndroidRuntime( 456): at com.android.internal.view.menu.MenuBuilder$MenuType.getMenuView(MenuBuilder.java:210)
E/AndroidRuntime( 456): at com.android.internal.view.menu.MenuBuilder.getMenuView(MenuBuilder.java:344)
E/AndroidRuntime( 456): at com.android.internal.policy.impl.PhoneWindow.initializePanelContent(PhoneWindow.java:841)
E/AndroidRuntime( 456): at com.android.internal.policy.impl.PhoneWindow.openPanel(PhoneWindow.java:417)
E/AndroidRuntime( 456): at com.android.internal.policy.impl.PhoneWindow.onKeyUpPanel(PhoneWindow.java:604)
E/AndroidRuntime( 456): at com.android.internal.policy.impl.PhoneWindow.onKeyUp(PhoneWindow.java:1320)
E/AndroidRuntime( 456): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1649)
E/AndroidRuntime( 456): at android.view.ViewRoot.deliverKeyEventToViewHierarchy(ViewRoot.java:2471)
E/AndroidRuntime( 456): at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2441)
E/AndroidRuntime( 456): at android.view.ViewRoot.handleMessage(ViewRoot.java:1735)
E/AndroidRuntime( 456): at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime( 456): at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime( 456): at android.app.ActivityThread.main(ActivityThread.java:4627)
E/AndroidRuntime( 456): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime( 456): at java.lang.reflect.Method.invoke(Method.java:521)
E/AndroidRuntime( 456): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
E/AndroidRuntime( 456): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
E/AndroidRuntime( 456): at dalvik.system.NativeStart.main(Native Method)