twisted.internet.gireactor.GIReactor.registerGApplication(self, app) method documentation

Register a Gio.Application or Gtk.Application, whose main loop will be used instead of the default one.

We will hold the application so it doesn't exit on its own. In versions of python-gi 3.2 and later, we exit the event loop using the app.quit method which overrides any holds. Older versions are not supported.