from gi.repository import Gtk

from gi.repository import Gio

import sys

class MyWindow(Gtk.ApplicationWindow):

    # constructor for a window (the parent window) with a label

    def __init__(self, app):

        Gtk.Window.__init__(self, title="GMenu Example", application=app)

        self.set_default_size(400, 200)

        label = Gtk.Label()

        label.set_text("This application goes boom!")

        self.add(label)

        # create the message_action (a Gio.SimpleAction) - for the window

        message_action = Gio.SimpleAction.new("message", None)

        # connect the signal from the action to the function message_cb()

        message_action.connect("activate", self.message_cb)

        # add the action to the application

        app.add_action(message_action)

    # callback function for the signal "activate" from the message_action

    # in the menu of the parent window

    def message_cb(self, action, parameter):

        # a Gtk.MessageDialog

        messagedialog = Gtk.MessageDialog(parent=self,

                                          flags=Gtk.DialogFlags.MODAL,

                                          type=Gtk.MessageType.WARNING,

                                          buttons=Gtk.ButtonsType.OK_CANCEL,

                                          message_format="This action will cause the universe to stop existing.")

        # connect the response (of the button clicked) to the function

        # dialog_response()

        messagedialog.connect("response", self.dialog_response)

        # show the messagedialog

        messagedialog.show()

    def dialog_response(self, widget, response_id):

        # if the button clicked gives response OK (-5)

        if response_id == Gtk.ResponseType.OK:

            print("*boom*")

        # if the button clicked gives response CANCEL (-6)

        elif response_id == Gtk.ResponseType.CANCEL:

            print("good choice")

        # if the messagedialog is destroyed (by pressing ESC)

        elif response_id == Gtk.ResponseType.DELETE_EVENT:

            print("dialog closed or cancelled")

        # finally, destroy the messagedialog

        widget.destroy()

class MyApplication(Gtk.Application):

    def __init__(self):

        Gtk.Application.__init__(self)

    def do_activate(self):

        win = MyWindow(self)

        win.show_all()

    def quit_cb(self, action, parameter):

        self.quit()

    def do_startup(self):

        Gtk.Application.do_startup(self)

        # create a menu (a Gio.Menu)

        menu = Gio.Menu()

        # append a menu item with label "Message" and action "app.message"

        menu.append("Message", "app.message")

        # append a menu item with label "Quit" and action "app.quit"

        menu.append("Quit", "app.quit")

        # set menu as the menu for the application

        self.set_app_menu(menu)

        # a new simpleaction - for the application

        quit_action = Gio.SimpleAction.new("quit", None)

        quit_action.connect("activate", self.quit_cb)

        self.add_action(quit_action)

app = MyApplication()

exit_status = app.run(sys.argv)

sys.exit(exit_status)