filtre-typo.php

<?php

add_filter( 'the_title', 'willy_insert_missing_unsecable' );
add_filter( 'the_content', 'willy_insert_missing_unsecable' );
function willy_insert_missing_unsecable( $text ) {
    $patterns = array( 
        '« ' => '«&nbsp;',
        ' »' => '&nbsp;»',
        ' :' => '&nbsp;:',
        ' !' => '&nbsp;!',
        ' ?' => '&nbsp;?',
        ' ;' => '&nbsp;;',
    );

    return str_replace( array_keys( $patterns ), array_values( $patterns ), $text );
}