public function loadItemType($type)
    {
        $signature = md5($type);
        if (isset($this->_buttons[$signature])) {
            return $this->_buttons[$signature];
        }

        list($plugin, $name) = pluginSplit($type);
        $alias = Slug::filter($name, '_');
        $aliasClass = Inflector::classify($alias);

        $className = $this->_getItemClassName($plugin, $aliasClass);

        if (!$className) {
            return false;
        }

        $this->_buttons[$signature] = new $className($this);
        return $this->_buttons[$signature];
    }