code: protected function createButtonGroup($groupName)
      {
          $groupConfig = Config::inst()->get("BetterButtonsGroups", $groupName);
          $label = (isset($groupConfig['label'])) ? $groupConfig['label'] : $groupName;
          $buttons = (isset($groupConfig['buttons'])) ? $groupConfig['buttons'] : array ();
          $button = DropdownFormAction::create(_t('GridFieldBetterButtons.'.$groupName, $label));
          foreach ($buttons as $b => $bool) {
              if ($bool) {
                  if ($child = $this->instantiateButton($b)) {
                      $button->push($child);
                  }
              }
          }
  
          return $button;
      }
docs: Creates a button group {@link DropdownFormAction}
  @param  string                           $groupName The name of the group
  @return DropdownFormAction