C# WebBrowser替Iframe内的网页赋值

C# WebBrowser为Iframe内的网页赋值

void?Button1Click(object?sender,?EventArgs?e)

??{

???this.webBrowser1.Document.Window.Frames[0].Document.GetElementsByTagName("TEXTAREA")[0].SetAttribute("value",?"程序赋值结果");

??}