A WordPress must-use plugin for easily switching between WP-palvelu.fi shadows
This plugin as of commit bfb019a923838bf60fbc3bad652c823303b09239 was merged into the Seravo Plugin, in pull request Seravo/seravo-plugin#36.
All future development goes there and this repository will eventually be deleted in 2018 or so.
You can insert your own admin notice for users that are in shadow
function my_shadow_admin_notice($admin_notice, $current_screen) {
return '<div class="notice notice-error"><p>This is staging. All content edited here will be lost. Return to production to create or edit content.</p></div>';
}
add_filter( 'wpp_instance_switcher_admin_notice', 'my_shadow_admin_notice', 10, 2 );