WP_Widget_Categories::__construct

	public function __construct() {
		$widget_ops = array(
			'classname'                   => 'widget_categories',
			'description'                 => __( 'A list or dropdown of categories.' ),
			'customize_selective_refresh' => true,
		);
		parent::__construct( 'categories', __( 'Categories' ), $widget_ops );
	}