code: protected function getDefaultButtonList($config)
      {
          $new = ($this->owner->ID == 0);
          $list = $new
              ? Config::inst()->get($config, $this->checkVersioned() ? "versioned_create" : "create")
              : Config::inst()->get($config, $this->checkVersioned() ? "versioned_edit" : "edit");
  
          return $list ?: array ();
      }
docs: Gets an array of all the default buttons as defined in the config
  @param  array $config
  @return array