Tendu should only add its new body classes instead of rebuild existing body classes

Drupal set for us many body classes. so we dont need to define them again:
I suggest we only add the with-sidbar... body classes intead of rebuild the whole $vars['body_classes']
I tested this code and got all the body classes as with the former version.
here is my suggestion:

function phptemplate_preprocess_page(&$vars) {  // Build array of helpful body classes
  $body_classes = array();
  if ($vars['left']) {
    $body_classes[] = 'with-sidebar-left';
  }
  if ($vars['right']) {
    $body_classes[] = 'with-sidebar-right';
  }
  $body_classes = array_filter($body_classes); // Remove empty elements
  $body_classes = implode(' ', $body_classes);// Create class list separated by spaces
  $vars['body_classes'] = $vars['body_classes'] .  $body_classes; //add tendu body classes to drupal default body classes
}