<?php/** * Wraps comments in a collapsible fieldset. */function YOUR_THEME_preprocess_comment_wrapper(&$variables) {  // Provide contextual information.  $variables['node'] = $variables['content']['#node'];  $variables['display_mode'] = variable_get('comment_default_mode_' . $variables['node']->type, COMMENT_MODE_THREADED);  // The comment form is optional and may not exist.  $variables['content'] += array('comment_form' => array());  $commentslist = $variables['content']['comments'];  $variables['content']['comments'] = array(    '#type' => 'fieldset',    '#title' => format_plural($variables['node']->comment_count, '1 comment', '@count comments'),    '#weight' => 0,    //'#collapsible' => TRUE, // does not work and thus is not necessary    //'#collapsed' => TRUE, // does not work and thus is not necessary    '#pre_render' => array(),    '#attributes' => array(),  );  // Make it manually collapsible as we cannot use #collapsible without the  // FAPI element processor.  $variables['content']['comments']['#attached']['library'][] = array('system', 'drupal.collapse');  $variables['content']['comments']['#attributes']['class'][] = 'collapsible';  $variables['content']['comments']['#attributes']['class'][] = 'collapsed';  $variables['content']['comments']['commentslist'] = $commentslist;}?>