public mshtml.IHTMLDocument2 GetHtmlDocument(int hwnd)
        {
            System.Object domObject = new System.Object();
            int tempInt = 0;
            System.Guid guidIEDocument2 = new Guid();
            int WM_Html_GETOBJECT =Win32API.RegisterWindowMessage("WM_Html_GETOBJECT");//定义一个新的窗口消息
            int W = Win32API.SendMessage(hwnd, WM_Html_GETOBJECT, 0, ref tempInt);//注:第二个参数是RegisterWindowMessage函数的返回值
            int lreturn = Win32API.ObjectFromLresult(W, ref guidIEDocument2, 0, ref domObject);
            mshtml.IHTMLDocument2 doc = (mshtml.IHTMLDocument2)domObject;
            return doc;
        }