Theming restricted text so that people knows which part is restricted (and do not include that part in there reply)

Better yet. Let's put the entire formatting logic to the theming function:

/**
 * Implementation of hook_theme().
 */
function restricted_text_theme() {
  return array(
    'restricted_text_format' => array(
      'arguments' => array('allowed' => true, 'key' => NULL, 'params' => NULL, 'interior' => NULL),
    ),
  );
}

function theme_restricted_text_format($allowed, $key, $params, $interior) {
  if($allowed)
    return $interior;
  else
    return '';
}

In function _restricted_text_replace_callback the following code:

  if ($reduced) {
    return $interior;
  }
  else {
    return '';
  }

Becomes:

  $formatted_restricted_text = theme('restricted_text_format', $reduced, $m['key'], $m['params'], $m['interior']);
  return $formatted_restricted_text;    

From my own custom module (or template)

function phptemplate_restricted_text_format($allowed, $key, $params, $interior) {
  if($allowed)
  {
    $param_exist = (count($params)>1?true:false);
    if(count($params) == 1)
      $param_exist = ($params[0]==''?false:true);

    if($param_exist)
      $param_display = implode(',',$params);
    else
      $param_display = $key; 

    $restricted = t('Restricted');    
    return '<div style=background-color:#FFF4C8;><u>'.$restricted.': '.$param_display.'</u><br><i>'.$interior.'</i></div>';
  }
  else
    return '';
}

You need to clear the cache to see it in effect. See http://drupal.org/node/173880

To clear the theme registry, do one of the following things:

>> On the "Administer > Site configuration > Performance" page, click on the "Clear cached data" button.
>> With devel block enabled (comes with devel module), click the "Empty cache" link.
>> The API function drupal_rebuild_theme_registry.

Patch