如何为TopLevel设置标题

Question

我想为TopLevel设置标题。我认为，我的密码对应于TkInter文档中的示例。您能解释一下，为什么master.title = 'Top'中的命令class AppTop（在下一个脚本中）没有为“ TopLevel”设置标题？谢谢！

import tkinter as tk

class AppTop(tk.Frame):

    def __init__(self, master):
        mon_h = 900
        mon_w = 1250

        master.title = 'Top'

        tk.Frame.__init__(self, master)
        master.minsize(height = 900, width = 600)

        fr_button = tk.Frame(master)
        fr_button.place(relx=0.01, rely=0.06)

        butArrowPlus = tk.Button(fr_button, text=">", height = 1, width = 20, command=self.Cmd)
        butArrowPlus.grid(column= 1, row= 1)
        return

    def Cmd(self):
        return

class Application(tk.Frame):
    def __init__(self, master):
        tk.Frame.__init__(self, master)

        frRoot = tk.Frame(master, width=700, height=400, bd=2)
        frRoot.place(relx=0.1, rely=0.1, anchor="nw")

        butIllumBall = tk.Button(frRoot, text= 'Light Ball', height = 1, width = 20, command=self.cmd_illuminated_ball)
        butIllumBall.grid(column= 0, row= 0, pady=10)

        master.minsize(height = 250, width = 300)
        master.title('Root')

    def cmd_illuminated_ball(self):

        top = tk.Toplevel()
        top.transient(self.master)        
        top.grab_set()                   
        app = AppTop(master = top)
        app.mainloop()
        return

wndRoot = tk.Tk()
appapp = Application(master=wndRoot)
appapp.mainloop()