Example: Hello World GUI with grid

# use grid to place widgets in 3x4 cells:

hwtext.grid(row=0, column=0, columnspan=4, pady=20)
r_label.grid(row=1, column=0)
r_entry.grid(row=1, column=1)
compute.grid(row=1, column=2)
s_label.grid(row=1, column=3)
quit_button.grid(row=2, column=0, columnspan=4, pady=5, 
                 sticky='ew')