定义theme和style, 注意是actionOverflowMenuStyle 和 android:windowBackground.(实测5.1.1和7.1.1)
<style name="AppTheme" parent="Theme.AppCompat.Light">
<item name="actionOverflowMenuStyle">@style/CustomActionOverflowMenuStyle</item>
<item name="android:windowBackground">@android:color/white</item>
</style>

<style name="CustomActionOverflowMenuStyle" parent="Widget.AppCompat.Light.PopupMenu.Overflow">
<item name="android:overlapAnchor">false</item>
<item name="android:popupBackground">@android:color/white</item>
</style>

refer to：http://stackoverflow.com/questions/19659637/how-to-change-the-background-color-of-action-bars-option-menu-in-android-4-2