tkinter_app6.py

# a proper app needs some buttons too!
button_run = tk.Button(bottom_frame, text="Start", command=run_app, bg='dark green', fg='white', relief='raised', width=10, font=('Helvetica 9 bold'))
button_run.grid(column=0, row=0, sticky='w', padx=100, pady=2)

button_close = tk.Button(bottom_frame, text="Exit", command=close_app, bg='dark red', fg='white', relief='raised', width=10, font=('Helvetica 9'))
button_close.grid(column=1, row=0, sticky='e', padx=100, pady=2)

window.mainloop()