title: Can't get tkinter window title to change from 'tk'
body: <p>I thought the line to change the title of a window was:</p>
  
  <pre><code>tk=Tk()
  
  tk.title="my title"
  </code></pre>
  
  <p>But I can't get the title to change in my code:</p>
  
  <pre><code>def welcome_screen():
      #creates the login window
      window = Tk()
      window.title = "Login Screen"
      window.geometry("960x540+450+250")
      canvas = Canvas(window, width=960, height=540, bd=10, bg='#494949')
      canvas.pack()
      window.mainloop()
  
  welcome_screen()
  </code></pre>
  
  <p>The title should change to "login screen" but when run it just says 'tk'.
  everything else works as expected.</p>