from gi.repository import Gtk
import sys


class MyWindow(Gtk.ApplicationWindow):

    def __init__(self, app):
        Gtk.Window.__init__(
            self, title="ScrolledWindow Example", application=app)
        self.set_default_size(200, 200)

        # the scrolledwindow
        scrolled_window = Gtk.ScrolledWindow()
        scrolled_window.set_border_width(10)
        # there is always the scrollbar (otherwise: AUTOMATIC - only if needed
        # - or NEVER)
        scrolled_window.set_policy(
            Gtk.PolicyType.ALWAYS, Gtk.PolicyType.ALWAYS)

        # an image - slightly larger than the window...
        image = Gtk.Image()
        image.set_from_file("gnome-image.png")

        # add the image to the scrolledwindow
        scrolled_window.add_with_viewport(image)

        # add the scrolledwindow to the window
        self.add(scrolled_window)


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)