
      opened: {
        observer: '_openedChanged',
        type: Boolean,
        value: false,
        notify: true
      },

      /**
       * True if the overlay was canceled when it was last closed.
       */
      canceled: {
        observer: '_canceledChanged',
        readOnly: true,
        type: Boolean,
        value: false
      },

      /**
       * Set to true to display a backdrop behind the overlay. It traps the focus
       * within the light DOM of the overlay.
       */
      withBack