def __init__(self, assets_dir=None, requirements_file="requirements.yml"):
        self.assets_dir = assets_dir or Path(".") / "assets"
        self.requirements = GroupedRequirements()
        self.requirements.load(requirements_file)
        self.temp_dir = mkdtemp()
def _init_signals(self):
        """Initializes the backends and gtk signals """
        self.connect("cursor-changed", self.on_select_row)
        _signals = BackendSignals()
        _signals.connect(_signals.BACKEND_ADDED, self.on_backend_added)
        _signals.connect(_signals.BACKEND_STATE_TOGGLED,
                         self.on_backend_state_changed)