title: Open another tkinter program from a main file
body: <p>I have try this in my main program</p>
  
  <pre><code>from tkinter import *
  import tkinter.filedialog
  import os
  root = Tk()
  def open():
      PathPy = tkinter.filedialog.askopenfilename(title="Open a file",filetypes=[('PYTHON file','.py')])
      os.system(PathPy)
  B = Button(root, text="Open a file", command=open).pack()
  root.mainloop()
  </code></pre>
  
  <p>and just this in my second file:</p>
  
  <pre><code>from tkinter import *
  root2 = Tk()
  root2.mainloop()
  </code></pre>
  
  <p>When I choose the python file, nothing happens... Can you please, tell me how to fix this ?</p>