Called when prefs dialog is running in standalone mode. It
    makes the delete event of dialog and click on close button finish
    the application.

def setup_standalone_signals(instance):
    """Called when prefs dialog is running in standalone mode. It
    makes the delete event of dialog and click on close button finish
    the application.
    """
    window = instance.get_widget('config-window')
    window.connect('delete-event', Gtk.main_quit)

    # We need to block the execution of the already associated
    # callback before connecting the new handler.
    button = instance.get_widget('button1')
    button.handler_block_by_func(instance.gtk_widget_destroy)
    button.connect('clicked', Gtk.main_quit)

    return instance