title: My inherited class MenuBar(tk.Menu) does not showing Menubar
body: <p>I have been trying to add a main menu to my program and am having trouble with it.
  I don't exactly understand the class structure of python3 as I'm fairly new to programming with it. 
  I am running on ubuntu 18.04 and here is the code I am having trouble with. </p>
  
  <pre><code>#! /usr/bin/env python3
  
  import tkinter as tk
  from tkinter import *
  
  class Application(tk.Tk):
  
      def __init__(self, *args, **kwargs):
          tk.Tk.__init__(self, *args, **kwargs)
          container = tk.Frame(self)
  
          menubar = MenuBar(self)
          self.config(menu=menubar)
  
      def quitButton(self):
          self.destroy()
  
  class MenuBar(tk.Menu):
      def __init__(self, parent):
          tk.Menu.__init__(self, parent)
          self.controller = parent
  
          menubar = tk.Menu(self, tearoff=False)
          filemenu = tk.Menu(menubar, tearoff=0)
          filemenu.add_command(label="Test", command=self.test_Test)
          filemenu.add_separator()
          filemenu.add_command(label="Exit", command=lambda:    self.controller.quitButton())
          menubar.add_cascade(label="File", menu=filemenu)
  
      def test_Test(self):
          print("This is a test")
  
  if __name__ == "__main__":
      app = Application()
      app.title("test") 
      app.mainloop()
  </code></pre>
  
  <p>The file menu does not appear for me. Any Help?</p>