materio-base-d7/modules/overlay/overlay.install

<?php

/**
 * @file
 * Install, update, and uninstall functions for the Overlay module.
 */

/**
 * Implements hook_enable().
 *
 * If the module is being enabled through the admin UI, and not from an
 * installation profile, reopen the modules page in an overlay.
 */
function overlay_enable() {
  if (strpos(current_path(), 'admin/modules') === 0) {
    // Flag for a redirect to <front>#overlay=admin/modules on hook_init().
    $_SESSION['overlay_enable_redirect'] = 1;
  }
}