protected override void OnDocumentComplete(object sender, EventArgs args) { MyBrowser hostBrowser = Host.Browser as MyBrowser; if (hostBrowser != null) { IHTMLElement el = browser.GetElementByID(true, "content"); string selectText = hostBrowser.GetSelectedText(true, false); if (selectText == null) { selectText = "请选择要收藏的文本"; el.setAttribute("placeholder", selectText, 0); } else { el.setAttribute("value", selectText, 0); } } }