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 _setup_drag(self, item):
    self._drag_and_drop_context.setup_drag(
      # Using the entire item allows dragging only by the label rather than the
      # widget itself. This avoids problems with widgets such as spin buttons
      # that do not behave correctly when reordering and also avoids accidental
      # clicking and modifying the widget by the user.
      item.widget,
      self._get_drag_data,
      self._on_drag_data_received,
      [item],
      [item],
      self)