如何在SilverStripe的管理区域自定义组件？

use SilverStripe\Forms\LiteralField;
use SilverStripe\Forms\TextField;
use SilverStripe\Widgets\Model\Widget;

class CustomWidget extends Widget
{
    private static $title = 'Custom Widget';

    private static $db = [
        'CustomContent' => 'Text'
    ];

    public function getCMSFields()
    {
        $fields = parent::getCMSFields();

        $fields->addFieldToTab('Root.Main', TextField::create('CustomContent', 'Custom Content'));

        return $fields;
    }

    public function Content()
    {
        return $this->CustomContent;
    }
}

SilverStripe\Widgets\Model\Widget:
  widgets:
    - CustomWidget

vendor/bin/sake dev/tasks/UpgradeSilverstripe