Preview message on invite form

On line 839 in invite.module, the field is set to preview the message but no value is given. I've written a theme hook for template.php that will add the message back to the invite page:

function mytheme_invite_form($form)
{
	if (arg(0) == 'invite')
	{
		$template = t(_invite_get_mail_template());
		$tokens = _invite_token_types($invite);
		$body = token_replace_multiple($template, $tokens);
  		$form['body'] = array(
			'#type' => 'item',
			'#title' => t('Preview message'),
			'#value' => '<div id="body-preview">' . $body . '</div>',
		);
	}
	return drupal_render($form);
}