public function __construct() {

		// Achievements.
		new LLMS_Meta_Box_Achievement();
		new LLMS_Meta_Box_Achievement_Sync();

		// Certs.
		new LLMS_Meta_Box_Certificate();
		new LLMS_Meta_Box_Certificate_Sync();

		// Emails.
		new LLMS_Meta_Box_Email_Settings();

		// Engagements.
		new LLMS_Meta_Box_Engagement();

		// Award Engagements.
		new LLMS_Meta_Box_Award_Engagement_Submit();

		// Membership restriction metabox.
		new LLMS_Meta_Box_Access();

		// Courses.
		new LLMS_Meta_Box_Course_Options();

		// Memberships.
		new LLMS_Meta_Box_Membership();

		// Courses & memberships.
		require_once 'meta-boxes/class.llms.meta.box.course.builder.php';
		require_once 'meta-boxes/class.llms.meta.box.visibility.php';
		require_once 'meta-boxes/class.llms.meta.box.instructors.php';
		new LLMS_Meta_Box_Product();
		new LLMS_Meta_Box_Students();

		// Lessons.
		require_once 'meta-boxes/class.llms.meta.box.lesson.php';

		// Coupons.
		new LLMS_Meta_Box_Coupon();

		// Orders.
		new LLMS_Meta_Box_Order_Submit();
		new LLMS_Meta_Box_Order_Details();
		new LLMS_Meta_Box_Order_Transactions();
		new LLMS_Meta_Box_Order_Enrollment();
		new LLMS_Meta_Box_Order_Notes();

		// Vouchers.
		new LLMS_Meta_Box_Voucher();

		add_action( 'add_meta_boxes', array( $this, 'hide_meta_boxes' ), 10 );
		add_action( 'add_meta_boxes', array( $this, 'refresh_meta_boxes' ), 10 );
		add_action( 'add_meta_boxes', array( $this, 'get_meta_boxes' ), 10 );
		add_action( 'save_post', array( $this, 'save_meta_boxes' ), 10, 2 );

		add_action( 'lifterlms_process_llms_voucher_meta', 'LLMS_Meta_Box_Voucher_Export::export', 10, 2 );

		// Error handling.
		add_action( 'admin_notices', array( $this, 'display_errors' ) );
		add_action( 'shutdown', array( $this, 'set_errors' ) );

		// Modify the title placeholder text for achievement and certificate templates.
		add_filter( 'enter_title_here', array( $this, 'maybe_modify_title_placeholder' ), 10, 2 );

		// Add default image information for achievement and certificate templates.
		add_filter( 'admin_post_thumbnail_html', array( $this, 'maybe_modify_post_thumbnail_html' ), 10, 3 );

	}