设置toolbar中弹出的menu菜单在toolbar的底部显示
<style name="toolbarMenu">
<item name="actionOverflowMenuStyle">@style/OverflowMenuStyle</item>
</style>
<style name="OverflowMenuStyle" parent="Widget.AppCompat.Light.PopupMenu.Overflow">
<item name="overlapAnchor">false</item> <!--设置不覆盖锚点-->
</style>