drop: {
        observer: '_withBackdropChanged',
        type: Boolean
      },

      /**
       * Set to true to disable auto-focusing the overlay or child nodes with
       * the `autofocus` attribute` when the overlay is opened.
       */
      noAutoFocus: {
        type: Boolean,
        value: false
      },

      /**
       * Set to true to disable canceling the overlay with the ESC key.
       */
      noCancelOnEscKey: {
        type: Boolean,
        value: false
      },

      /**
       * Se