MainWindow.py (Código)

# -*- coding: utf-8 -*-
"""Gtk.InfoBar()."""
import gi
gi.require_version(namespace='Gtk', version='3.0')
from gi.repository import Gtk, Gio, GLib
@Gtk.Template(filename='MainWindow.ui')
class MainWindow(Gtk.ApplicationWindow):
    __gtype_name__ = 'MainWindow'
    info_bar = Gtk.Template.Child(name='info_bar')
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
    @Gtk.Template.Callback()
    def on_info_bar_button_clicked(self, widget, response):
        if response == Gtk.ResponseType.CLOSE:
            self.info_bar.set_revealed(revealed=False)
    @Gtk.Template.Callback()
    def on_button_clicked(self, widget):
        if not self.info_bar.get_revealed():
            self.info_bar.set_revealed(revealed=True)
            GLib.timeout_add_seconds(priority=0, interval=5, function=self.info_bar_timeout)
    def info_bar_timeout(self):
        self.info_bar.set_revealed(revealed=False)
class Application(Gtk.Application):
    def __init__(self):
        super().__init__(application_id='br.natorsc.Exemplo',
                         flags=Gio.ApplicationFlags.FLAGS_NONE)
    def do_startup(self):
        Gtk.Application.do_startup(self)
    def do_activate(self):
        win = self.props.active_window
        if not win:
            win = MainWindow(application=self)
        win.present()
    def do_shutdown(self):
        Gtk.Application.do_shutdown(self)
if __name__ == '__main__':
    import sys
    app = Application()
    app.run(sys.argv)