如何将长文本域添加到sitefinity上的自定义小工具？

public string LongTextField { get; set; }

public CustomWidget()
{
    LongTextField = "";
}

protected override void CreateChildControls()
{
    var longTextFieldControl = new TextFieldControl
    {
        ID = "LongTextFieldControl",
        Text = LongTextField,
        Rows = 5,
        Columns = 50
    };

    Controls.Add(longTextFieldControl);
}

protected override void InitializeControls(GenericContainer container)
{
    var longTextFieldControl = container.FindControl("LongTextFieldControl") as TextFieldControl;
    longTextFieldControl.Text = LongTextField;
}

public override void ExtractValues(IOrderedDictionary dictionary)
{
    var longTextFieldControl = FindControl("LongTextFieldControl") as TextFieldControl;
    LongTextField = longTextFieldControl.Text;

    base.ExtractValues(dictionary);
}