如何使用wp\\u nav\\u菜单用PHP折叠和扩展元素？一些walker功能？可能是插件？

What it looks like in wp-admin menus

About
    Customers
    Cases
Contact
    Contact us
    Contact someone else

On the front page - When I have not selected anything it should look like this

About
Contact

When I selected About it should look like this

About
    Customers
    Cases
Contact

When I selected Customers it should look like this

About
Contact
    Contact us
    Contact someone else