title: join thread after start_new_thread
body: <p>below function exits after 3 seconds when i run it separately, but when i call it in a thread it never exits. kindly suggest what is wrong in this code.</p>
  
  <pre><code>def display(val1, val2):
  
      root =  Tk()
      clock = Label(root, font=('times', 20, 'bold'), bg='white')
      clock.pack(fill=BOTH, expand=0)
      def tick():
          time1 = val1 +'\n' + val2
          clock.config(text=time1)
      tick()
      root.after(3000,root.quit)
      root.mainloop()
  </code></pre>
  
  <p>I am calling above function in my program as</p>
  
  <pre><code>thread.start_new_thread(display,(val1,val2))
  </code></pre>
  
  <p>thread starts appropriately and main program continues but the display function does not exit after 3 seconds, pls suggest how to join this thread or destroy it without affecting main program </p>