text: # -*- coding: utf-8 -*-
  """Gtk.Box() horizontal."""
  
  import gi
  
  gi.require_version(namespace='Gtk', version='3.0')
  
  from gi.repository import Gio, Gtk
  
  
  @Gtk.Template(filename='MainWindow.ui')
  class MainWindow(Gtk.ApplicationWindow):
      __gtype_name__ = 'MainWindow'
  
      def __init__(self, **kwargs):
          super().__init__(**kwargs)
  
  
  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)
  