Android 4后，Google
Google is happy to bid farewell to the Menu button, and they don’t even want you calling that funny little three-dot button the “menu.”
Rather, Google wants us to think of the menu at an “action overflow.”
When there isn’t enough space in the Action Bar for all the icons you might need in an app, the action overflow handles it.
编写兼容的程序从2.x-4.x ,在Eclipse ADT 里编译的时候就必须要选择高版本LEVEL API,
但在发布的时候，AndroidManifest.xml,要删除掉 android:targetSdkVersion="16" ，而只保留 android:minSdkVersion="10"
android 2.3.3 level api,则在Android 4.X 系统下，options menu出现在了系统导航条上的三点菜单里。
注意,options menu->action bar ->system navigation bar -> overflow menu 几个概念的演化。
如图
Google is happy to bid farewell to the Menu button, and they don’t even want you calling that funny little three-dot button the “menu.”
Rather, Google wants us to think of the menu at an “action overflow.”
When there isn’t enough space in the Action Bar for all the icons you might need in an app, the action overflow handles it.
编写兼容的程序从2.x-4.x ,在Eclipse ADT 里编译的时候就必须要选择高版本LEVEL API,
但在发布的时候，AndroidManifest.xml,要删除掉 android:targetSdkVersion="16" ，而只保留 android:minSdkVersion="10"
android 2.3.3 level api,则在Android 4.X 系统下，options menu出现在了系统导航条上的三点菜单里。
注意,options menu->action bar ->system navigation bar -> overflow menu 几个概念的演化。
如图
