maximize number of special characters in registeration in wordpress

WordPress don't accept member registration with special characters in username , i used the simple following plugin to resolve this issue , it is ok but the issue that maximum number of special characters member can use is 8 only , what can i increase it ? thanks alot

<?php

/*

Plugin Name: Wordpress Special Characters in Usernames

Plugin URI: http://www.oneall.com/

Description: Enables usernames containing special characters (russian, cyrillic, arabic) on your Wordpress Blog

Version: 1.2

Author: Claude Schlesser

Author URI: http://www.oneall.com/

License: GPL2

*/

/**

 * Overrides the Wordpress sanitize_user filter to allow special characters

 */

function wscu_sanitize_user ($username, $raw_username, $strict)

{

    //Strip HTML Tags

    $username = wp_strip_all_tags ($raw_username);



    //Remove Accents

    $username = remove_accents ($username);



    //Kill octets

    $username = preg_replace ('|%([a-fA-F0-9][a-fA-F0-9])|', '', $username);



    //Kill entities

    $username = preg_replace ('/&.+?;/', '', $username);



    //If strict, reduce to ASCII, Cyrillic and Arabic characters for max portability.

    if ($strict)

    {

        //Read settings

        $settings = get_option ('wscu_settings');



        //Replace

        $username = preg_replace ('|[^a-z\p{Arabic}\p{Cyrillic}0-9 _.\-@]|iu', '', $username);

    }



    //Remove Whitespaces

    $username = trim ($username);



    // Consolidate contiguous Whitespaces

    $username = preg_replace ('|\s+|', ' ', $username);



    //Done

    return $username;

}



add_filter ('sanitize_user', 'wscu_sanitize_user', 10, 3);

via Chebli Mohamed