reset() {
    this.isInitialViewSet = false;
    this.isInitialEventDispatched = false;

    this.#hideUINotification(/* reset = */ true);
    this.switchView(SidebarView.THUMBS);

    this.outlineButton.disabled = false;
    this.attachmentsButton.disabled = false;
    this.layersButton.disabled = false;
    this._currentOutlineItemButton.disabled = true;
  }
Callback used when the sidebar has been opened/closed, to ensure that
the viewers (PDFViewer/PDFThumbnailViewer) are updated correctly.