title: Why are multiple instances of Tk discouraged?
body: <p>Consider below example:</p>
  
  <pre><code>import tkinter as tk
  
  root = tk.Tk()
  root.title("root")
  
  other_window = tk.Tk()
  other_window.title("other_window")
  
  root.mainloop()
  </code></pre>
  
  <p>and also see below example that creates instances of <code>Tk</code> back-to-back instead of at once, so there's <em>exactly one</em> instance of <code>Tk</code> at any given time:</p>
  
  <pre><code>import tkinter as tk
  
  def create_window(window_to_be_closed=None):
      if window_to_be_closed:
          window_to_be_closed.destroy()
      window = tk.Tk()
      tk.Button(window, text="Quit", command=lambda arg=window : create_window(arg)).pack()
      window.mainloop()
  
  create_window()
  </code></pre>
  
  <ul>
  <li>Why is it considered bad to have multiple instances of <code>Tk</code>?</li>
  <li>Is the second snippet considered a bit better, or does it suffer from
  the same conditions the first code does?</li>
  </ul>