public function getTabs() {
		$tabs = [
			'global' => '\Pressbooks\Modules\ThemeOptions\GlobalOptions',
			'web' => '\Pressbooks\Modules\ThemeOptions\WebOptions',
			'pdf' => '\Pressbooks\Modules\ThemeOptions\PDFOptions',
			'ebook' => '\Pressbooks\Modules\ThemeOptions\EbookOptions',
		];

		if ( false === get_site_transient( 'pb_pdf_compatible' ) && false === \Pressbooks\Modules\Export\Prince\Filters::hasDependencies() ) {
			unset( $tabs['pdf'] );
		} else {
			set_site_transient( 'pb_pdf_compatible', true );
		}

		if ( false === get_site_transient( 'pb_epub_compatible' ) && false === \Pressbooks\Modules\Export\Epub\Epub201::hasDependencies() ) {
			unset( $tabs['ebook'] );
		} else {
			set_site_transient( 'pb_epub_compatible', true );
		}

		/**
		 * Add a custom tab to the theme options page.
		 *
		 * @since 3.9.7
		 *
		 * @param array $tabs
		 */
		return apply_filters( 'pb_theme_options_tabs', $tabs );
	}