private void reflectDocumentViewModeInButtons() {
        if (document == null) {
            return;
        }
        reflectSelectionInButton(
                singlePageViewContinuousButton, isDocumentViewMode(
                DocumentViewControllerImpl.ONE_COLUMN_VIEW));
        reflectSelectionInButton(
                facingPageViewNonContinuousButton, isDocumentViewMode(
                DocumentViewControllerImpl.TWO_PAGE_RIGHT_VIEW));
        reflectSelectionInButton(
                facingPageViewContinuousButton, isDocumentViewMode(
                DocumentViewControllerImpl.TWO_COLUMN_RIGHT_VIEW));
        reflectSelectionInButton(
                singlePageViewNonContinuousButton, isDocumentViewMode(
                DocumentViewControllerImpl.ONE_PAGE_VIEW));
    }