Drupal: Front theme on error 403 (Access denied)

gistfile1.aw

<?php

// To enable this, set 403 path to 'error-403' on admin/settings/error-reporting
// or do variable_set('site_403', 'error-403'); in a hook_update_N, in your .install file.

function mymodule_menu() {
  return array(
    'error-403' => array(
      'title'             => "Access denied",
      'page callback'     => 'mymodule_error_403',
      'access arguments'  => array('access content'),
    ),
  );
}

function mymodule_error_403() {
  // Always display front theme
  global $custom_theme;
  $custom_theme = FALSE;

  // Mimic default drupal 403
  drupal_set_title(t("Access denied"));
  return t("You are not authorized to access this page.");
}