Template files & all user messages

1. This file do not do anything anymore. In previous single message template there was no sidebar. Many things have changed in current version’s single message template. This file is there so that if any user want to use previous layout of single message, they can use this file.

2. Currently you can view all messages from Dashboard > Front End PM > All Messages, but this does not allow to show only for specific user.

Thank you. I find solution how to show messages for specific user

add_filter( 'fep_table_prepare_items_args', function( $args, $message_type ) {
    if( ! empty( $_GET['is_user_id'] )
    ) {
        $args['participant_query'][] = array(
            'mgs_participant' => trim( $_GET['is_user_id'] ),
        );
    }
    return $args;
}, 10, 2 );

And in admin panel I need just add to URL &is_user_id={USER_ID}