public function &addGroup($unshift = false)
    {
        $group = $this->factory->create('FormDesigner\FormGroup');

        if ($unshift == true) {
            array_unshift($this->groups, $group);
        }
        else {
            $this->groups[] = $group;
        }

        $group->injectFormDesigner($this);

        return $group;
    }