from gi.repository import Gtk

import sys

# a Gtk ApplicationWindow

class MyWindow(Gtk.ApplicationWindow):

    # constructor: the title is "Welcome to GNOME" and the window belongs

    # to the application app

    def __init__(self, app):

        Gtk.Window.__init__(self, title="Welcome to GNOME", application=app)

class MyApplication(Gtk.Application):

    # constructor of the Gtk Application

    def __init__(self):

        Gtk.Application.__init__(self)

    # create and activate a MyWindow, with self (the MyApplication) as

    # application the window belongs to.

    # Note that the function in C activate() becomes do_activate() in Python

    def do_activate(self):

        win = MyWindow(self)

        # show the window and all its content

        # this line could go in the constructor of MyWindow as well

        win.show_all()

    # start up the application

    # Note that the function in C startup() becomes do_startup() in Python

    def do_startup(self):

        Gtk.Application.do_startup(self)

# create and run the application, exit with the value returned by

# running the program

app = MyApplication()

exit_status = app.run(sys.argv)

sys.exit(exit_status)