Drupal doesn't put a CKeditor default on the summary of the body field. This module does :)

README

Drupal doesn't put a CKeditor default on the summary of the body field.
This module does :)

summaryeditor.info

name = "Summary's CKeditor"
description = "Module puts CKeditor on the Summary of the body field."
core = "7.x"
package = Fix
php = "5.2.4"
version = "7.x-1.0"
project = "custom"

;dependencies[] = "ckeditor"
dependencies[] = "wysiwyg"

summaryeditor.module

<?php
/**
 * @file
 * Custom code for your dupal 7 site
 */

/**
 * Implements hook_help().
 */
function summaryeditor_help($path, $arg) {
  $output = NULL;  
  switch ($path) {
    case 'admin/help#summaryeditor':
      //$output = file_get_contents(drupal_get_path('module', 'the_aim_custom') . '/README.txt');
      //return nl2br($output);
      return t('<h1>A fix for CKeditor on Summary body field.</h1>
      <p>Drupal doesn\'t put a CKeditor default on the summary of the body field. This module does ;)</h2>
      <h2>Usefull links:</h2>
      <ul>
      <li>Blog: <a href="http://theunraveler.com/blog/2012/drupal-7-how-add-wysiwyg-editor-text-summary-field/" target="_blank">blog post</a></li>
      <li>Drupal API: <a href="http://api.drupal.org/api/drupal/modules!field!field.api.php/function/hook_field_widget_form_alter/7" target="_blank">function hook_field_widget_form_alter(&$element, &$form_state, $context)</a></li>
      </ul>
      ');
  }
  return $output;
}


/**
 * Implementation of hook_field_widget_form_alter().
 *
 * Add WYSIWYG treatment to textarea summary form items.
 */
function summaryeditor_field_widget_form_alter(&$element, &$form_state, $context) {
  if (isset($element['summary'])) {
    drupal_add_css(drupal_get_path('module', 'summaryeditor') . '/assets/textarea-summary.css');
    drupal_add_js(drupal_get_path('module', 'summaryeditor') . '/assets/textarea-summary.js');
    $element['summary']['#type'] = 'text_format';
    $element['summary']['#format'] = $element['#format'];
  }
}

/**
 * Implements hook_field_attach_presave().
 */
function summaryeditor_field_attach_presave($entity_type, $entity) {
  list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);

  foreach (field_info_instances($entity_type, $bundle) as $instance) {
    $field = field_info_field_by_id($instance['field_id']);
    $field_name = $field['field_name'];
    if ($field['type'] == 'text_with_summary' && !empty($entity->$field_name)) {
      $language = isset($entity->language) ? $entity->language : LANGUAGE_NONE;
      foreach ($entity->$field_name[$language] as $id => &$value) {
        if (is_array($value['summary'])) {
          $value['summary'] = $value['summary']['value'];
        }
      }
    }
  }
}