主动管理子菜单问题

Question

我无法创建子菜单的子菜单

喜欢

父 - ＆GT;  Child1 - ＆gt; A.           乙

Child2

喜欢这个

menu.add label: "Parent", url: "" , priority: 3  do |widgets|
    widgets.add label: "Child1", url:"", priority: 1 do |A|
       A.add label: "A", url:""
       A.add label: "B", url:""
    end
    widgets.add label: "Child2", url:""
end