code: function() {
      if (!this._shape.dragging) {
        this._shape.dragging = new L.Handler.PathDrag(this._shape);
      }
      this._shape.dragging.enable();
      this._shape
        .on('dragstart', this._onStartDragFeature, this)
        .on('dragend', this._onStopDragFeature, this);
    }
docs: Adds drag start listeners