title: 'Window' object has no attribute '_tclCommands'
body: <p>I'm new to Python and am trying to make a code for class that needs either to clear the screen or make new windows, which I have tried both of but failed miserably. But besides that, I have tried to run this code with different modifications, and almost all the time I get the error: 'Window' object has no attribute '_tclCommands'. What does this error mean? Another thing that could be related to this is that I cannot close the window specifically, but instead need to quit out of IDLE, the error saying: 'Window' object has no attribute 'destroy'. What can I do to fix this?</p>
  
  <pre><code>from tkinter import *
  import time
  import os
  
  background_color = 'SlateGray'
  text_background_color = 'DarkViolet'
  
  class Window:
      def __init__(self, master):
          Frame.__init__(self, master)
          self.grid()
          self.create_widgets()
          self.configure(background = background_color)
  
      def create_widgets(self):
          self.button = Button(self, text = "Clear", command = clear_screen())
          self.button.grid(row = 1, column = 1)
  
      def clear_screen(self):
          self.Frame.grid_forget()
  
  
  
  root = Tk()
  root.configure(background = background_color)
  root.title("Guess Your Birthday")
  app = Window(root)
  root.mainloop()
  </code></pre>