如何在垂直Gtk.Box中水平居中放置Gtk.Grid？

box = Gtk.Box(orientation=Gtk.Orientation.VERTICAL, spacing=6)

grid = Gtk.Grid()
# 添加部件到Gtk.Grid

alignment = Gtk.Alignment()
alignment.set(0.5, 0, 0, 0)  # 设置水平居中
alignment.add(grid)

box.pack_start(alignment, True, True, 0)

import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk

# 创建一个垂直Gtk.Box
box = Gtk.Box(orientation=Gtk.Orientation.VERTICAL, spacing=6)

# 创建一个Gtk.Grid并添加所需的部件
grid = Gtk.Grid()
# 添加部件到Gtk.Grid

# 创建一个Gtk.Alignment并将Gtk.Grid放置在其中
alignment = Gtk.Alignment()
alignment.set(0.5, 0, 0, 0)  # 设置水平居中
alignment.add(grid)

# 将Gtk.Alignment添加到垂直Gtk.Box中
box.pack_start(alignment, True, True, 0)

# 显示窗口和运行Gtk主循环
window = Gtk.Window()
window.add(box)
window.show_all()
Gtk.main()