title: Not able to include widgets in a Toplevel container in Tkinter
body: <p>I have code using <code>Tkinter</code> that opens one window, then (after clicking a button) opens a <code>Toplevel</code> container. I'm trying to put an <code>Label</code> widget into this additional window, but keep getting an error saying "can't invoke label command: application has been destroyed."</p>
  
  <p>How can I keep my <code>root.Tk()</code> window open to avoid this error? </p>
  
  <p>Here's what my code looks like:</p>
  
  <pre><code>import Tkinter
  from Tkinter import *
  
  root = Tk()
  root.wm_title("First Window")
  
  
  NewWin = Button(root, text="Click Me!", command=newwin)
  NewWin.pack()
  
  
  def newwin():
      top = Toplevel()
      top.wm_title("Second Window")
  
  Praise = Label(top, text="Good Work!")
  Praise.grid()
  
  
  root.mainloop()
  </code></pre>
  
  <p>Up until the label I try to install in the second window, the code works. How can I keep both windows up and running?</p>