menu_demo.py

#!/usr/bin/env python3

# Python imports
import sys

# GTK imports
import gi
gi.require_version("Gtk", "3.0")
from gi.repository import Gio
from gi.repository import Gtk

class AppWindow(Gtk.ApplicationWindow):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self.set_border_width(10)
        self.set_default_size(640, 480)

        open_selection = Gtk.ModelButton(action_name="open_file", label="Open")
        about_selection = Gtk.ModelButton(action_name="about_application", label="About")

        vbox = Gtk.Box(orientation=Gtk.Orientation.VERTICAL, margin=10, spacing=10)
        vbox.add(open_selection)
        vbox.add(about_selection)
        vbox.show_all()

        self.popover = Gtk.Popover()
        self.popover.add(vbox)
        self.popover.set_position(Gtk.PositionType.BOTTOM)

        menu_button = Gtk.MenuButton(popover=self.popover)
        menu_icon = Gtk.Image.new_from_icon_name("open-menu-symbolic", Gtk.IconSize.MENU)
        menu_icon.show()
        menu_button.add(menu_icon)
        menu_button.show()

        headerbar = Gtk.HeaderBar()
        headerbar.props.show_close_button = True
        headerbar.props.title = "Hamburger Menu Demo"
        headerbar.add(menu_button)
        headerbar.show()
        self.set_titlebar(headerbar)

    def open_file(self, widget):
        print("Open file")

class Application(Gtk.Application):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, application_id="org.example.myapp")
        self.window = None

    def do_startup(self):
        Gtk.Application.do_startup(self)

        action = Gio.SimpleAction.new("open_file", None)
        action.connect("activate", self.open_file)
        action.set_enabled(True)
        self.add_action(action)

        action = Gio.SimpleAction.new("about_application", None)
        action.connect("activate", self.on_about)
        self.add_action(action)

        action = Gio.SimpleAction.new("quit", None)
        action.connect("activate", self.on_quit)
        self.add_action(action)

    def do_activate(self):
        # We only allow a single window and raise any existing ones
        if not self.window:
            # Windows are associated with the application
            # when the last one is closed the application shuts down
            self.window = AppWindow(application=self, title="Main Window")

        self.window.present()

    def open_file(self, action, param):
        print("Open file")

    def on_about(self, action, param):
        print("About application")

    def on_quit(self, action, param):
        self.quit()


if __name__ == "__main__":
    app = Application()
    app.run(sys.argv)