Here is a short plugin that adds the interim-login lightbox on every frontend page:
<?php /* Plugin Name: Interim Login Everywhere Version: 1.0.1 Plugin URI: http://nowhere.com Description: Provide interim login screens on all pages. Author: S Valentine */ function ile_enqueue_scripts() { // we only care to add scripts and styles if the user is logged in. if ( is_user_logged_in() ) { // add javascript file wp_register_script( 'wp_auth_check', '/wp-includes/js/wp-auth-check.js' , array('heartbeat'), false, 1); wp_localize_script( 'wp_auth_check', 'authcheckL10n', array( 'beforeunload' => __('Your session has expired. You can log in again from this page or go to the login page.'), 'interval' => apply_filters( 'wp_auth_check_interval', 3 * MINUTE_IN_SECONDS ), // default interval is 3 minutes ) ); wp_enqueue_script ('wp_auth_check'); // add css file wp_enqueue_style( 'wp_auth_check','/wp-includes/css/wp-auth-check.css', array( 'dashicons' ), NULL, 'all' ); // add the login html to the page add_action( 'wp_print_footer_scripts', 'wp_auth_check_html', 5 ); } } add_action( 'wp_enqueue_scripts', 'ile_enqueue_scripts' ); // make sure the stylesheet appears on the lightboxed login iframe function ile_enqueue_login_scripts() { wp_enqueue_style( 'wp_auth_check','/wp-includes/css/wp-auth-check.css', array( 'dashicons' ), NULL, 'all' ); } add_action( 'login_enqueue_scripts', 'ile_enqueue_login_scripts' ); ?>