我无法在tkinter中为另一个打开窗口

import tkinter as tk

class NewWindow(tk.Toplevel):
    def __init__(self, parent):
        tk.Toplevel.__init__(self, parent)
        self.title("New Window")
        self.geometry("200x200")
        # 添加窗口内容
        label = tk.Label(self, text="This is a new window")
        label.pack()

# 创建主窗口
root = tk.Tk()
root.title("Main Window")
root.geometry("300x300")

# 创建打开新窗口的按钮事件
def open_new_window():
    new_window = NewWindow(root)

# 创建按钮
button = tk.Button(root, text="Open New Window", command=open_new_window)
button.pack()

root.mainloop()