android Preview xml中显示actionbaroverlaylayout

> android Preview 中显示actionbaroverlaylayout
将style.xml文件中的  
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">  
修改为  
    <style name="AppTheme" parent="Base.Theme.AppCompat.Light.DarkActionBar"> 

<!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Base.Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>