我的课程中的 tkinter 小部件没有显示

Question

我正在尝试编写一个包含多个页面并且可以在单击按钮时切换到的代码。它最初有效，但我的小部件没有显示，并且既没有警告也没有错误消息。其次，使用tk和tk.TK有什么区别？

from tkinter import *

import tkinter as tk

class moreTab(tk.Tk):

    def __init__(self):

        Tk.__init__(self)

        self.geometry("1200x600")

        container = Frame(self, bg='#c9e3c1')

        container.pack(side = "top", fill = 'both', expand = True)

        container.grid_rowconfigure(0, weight = 1)

        container.grid_columnconfigure(0, weight = 1)

        self.frames = {}

        for q in (pageone, widget):

            frame = q(container,self)

            self.frames[q] = frame

            frame.place(x= 0,y = 0)

        self.raise_frame(pageone)

    def raise_frame(self,cont):

        frame = self.frames[cont]

        frame.tkraise()

class widget(Frame):

    def __init__(self, master, control):

        Frame.__init__(self, master)

        lab = tk.Label(self, text="main page")

        lab.place(x = 10, y = 40)

        but = tk.Button(self, text='visit start page', command=lambda: 

control.raise_frame(pageone))

        but.place(x = 10, y = 70)

class pageone(Frame):

    def __init__(self, master, control):

        Frame.__init__(self,master)

        lab = Label(self, text = 'welcome to Game Analysis')

        lab.place(x = 10, y = 10)

        but = Button(self, text = "Start", command  = lambda: 

control.raise_frame(widget))

        but.place(x = 10, y = 20)

app = moreTab()

app.mainloop()