from __future__ import print_function

#
# Create a GUI with a single push button
#
try:
    import Tkinter
except ImportError:
    import tkinter as Tkinter

# I like having a Frame object as the top-level GUI
# "application" element that contains everything else.
# Since I don't give Frame any arguments, it gets
# placed in a window all by itself.
app = Tkinter.Frame()

# Grid is part of "geometry management".  The three
# most commonly used arguments are "row", "column"
# and "sticky".  As implied by the name, grid places
# widgets in a grid.  "row" and "column" specify the
# position in the grid.  "sticky" specifies which side
# of the widget is "attached" to the container frame.
# In this case, "nsew" means "north", "south", "east"
# and "west", so all four sides of "app" are sticking
# to the container (which happens to be the GUI window).
# If the window is resized, then "app" will get resized
# as well.
app.grid(row=0, column=0)

# Now we create a button inside our "app" frame, as
# specified by the first argument.  "app" is called the
# "parent" widget of "button"; and "button" is called
# a "child" widget of "app".  The label in the button
# is specified in the "text" argument.
button = Tkinter.Button(app, text="Click me")

# We need to specify where "button" is placed relative
# to "app".  In this case, we put it in row 0, column 0.
# Tkinter is pretty smart about grid positioning, so
# things that look like they should work usually do.
button.grid(row=0, column=0)

# Finally, we enter the GUI event loop.
app.mainloop()

# We get here when the event loop terminates, eg when
# the window is closed.
print("Finished")