from gi.repository import Gtk

import sys

class MyWindow(Gtk.ApplicationWindow):

    # a window

    def __init__(self, app):

        Gtk.Window.__init__(

            self, title="ToggleButton Example", application=app)

        self.set_default_size(300, 300)

        self.set_border_width(30)

        # a spinner animation

        self.spinner = Gtk.Spinner()

        # with extra horizontal space

        self.spinner.set_hexpand(True)

        # with extra vertical space

        self.spinner.set_vexpand(True)

        # a togglebutton

        button = Gtk.ToggleButton.new_with_label("Start/Stop")

        # connect the signal "toggled" emitted by the togglebutton

        # when its state is changed to the callback function toggled_cb

        button.connect("toggled", self.toggled_cb)

        # a grid to allocate the widgets

        grid = Gtk.Grid()

        grid.set_row_homogeneous(False)

        grid.set_row_spacing(15)

        grid.attach(self.spinner, 0, 0, 1, 1)

        grid.attach(button, 0, 1, 1, 1)

        # add the grid to the window

        self.add(grid)

    # callback function for the signal "toggled"

    def toggled_cb(self, button):

        # if the togglebutton is active, start the spinner

        if button.get_active():

            self.spinner.start()

        # else, stop it

        else:

            self.spinner.stop()

class MyApplication(Gtk.Application):

    def __init__(self):

        Gtk.Application.__init__(self)

    def do_activate(self):

        win = MyWindow(self)

        win.show_all()

    def do_startup(self):

        Gtk.Application.do_startup(self)

app = MyApplication()

exit_status = app.run(sys.argv)

sys.exit(exit_status)