/**
   * Implements hook_form_alter.
   * Client wants the subject field to initially be blank.
   * If the user doesn't type in a subject line, then the
   * node title should be inserted in the subject field.
  * Currently in the code below, the form_alter puts the node title as the 
  * #default_value in the subject field.
   */
function external_page_form_alter($form_id, &$form) {
  $site = strtok($_SERVER['SERVER_NAME'], '.');
  switch ($form_id) {
    case 'comment_form' :
      if ($site == 'comments') {
      	$subject = 'Re: ' . drupal_get_title();
       $form['subject'] = array (
       '#type' => textfield,
       '#title' => 'Subject', 
       '#default_value' => decode_entities($subject),
       );
      }
    break;    
  }
}
function external_page_comment_form_validate($form_id, $form_values) {
	//Not validating anything just now.
}
function external_page_comment_form_submit($form, $form_values) {

/**
  * Note: this code doesn't work, what happens is that if the subject field is blank
  * then it somehow gets populated with the first part of the first sentence i of the
  * text in the the comment field.
 */
	
 if ($form_values['subject'] == '') {
    $subject = 'Re: ' . drupal_get_title();
    $form_values['subject'] = $subject;
    //form_set_value($form_values['subject'], $subject);
  }
}