用webbrowser控件 打开下载文件的路径时，文件不能下载时一闪就过。具体代码如下

Question

///
/// 主要作用是屏蔽IFRAME 类的JS错误
///
public partial class WebbrowserExt : System.Windows.Forms.WebBrowser
{
public string BaseUrl = string.Empty;
public WebbrowserExt()
{
InitializeComponent();
this.AllowWebBrowserDrop = false;
(this.ActiveXInstance as SHDocVw.WebBrowser).NewWindow3 += WebbrowserExt_NewWindow3;
(this.ActiveXInstance as SHDocVw.WebBrowser).FileDownload += WebbrowserExt_FileDownload;
}

    public WebbrowserExt(IContainer container)
    {
        container.Add(this); 
        InitializeComponent(); 
        this.AllowWebBrowserDrop = false; 
        var IhtmlDocument3 = (IHTMLDocument3)this.Document.DomDocument; 
        IhtmlDocument3.enableDownload = false; 
        (this.ActiveXInstance as SHDocVw.WebBrowser).NewWindow3 += WebbrowserExt_NewWindow3; 
        (this.ActiveXInstance as SHDocVw.WebBrowser).FileDownload += WebbrowserExt_FileDownload;
    }

    void WebbrowserExt_FileDownload(bool ActiveDocument, ref bool Cancel)
    {
        //取消默认的文件下载
        if (!ActiveDocument)
            Cancel = true;
    }

    void WebbrowserExt_NewWindow3(ref object ppDisp, ref bool Cancel, uint dwFlags, string bstrUrlContext, string bstrUrl)
    { 
        BaseUrl = bstrUrl;
    }

    private SHDocVw.IWebBrowser2 Iwb2; 
    protected override void AttachInterfaces(object nativeActiveXObject)
    {
        Iwb2 = (SHDocVw.IWebBrowser2)nativeActiveXObject;
        Iwb2.Silent = true;
        base.AttachInterfaces(nativeActiveXObject);
    }

    protected override void DetachInterfaces()
    {
        Iwb2 = null;
        base.DetachInterfaces();
    }
}

改写的webbrowser如上。
如下是调用。
///
/// 创建新选项卡
///
///
///
private void WebBrowser_NewWindow(object sender, CancelEventArgs e)
{
string strurl;
var wb = new WebbrowserExt();
wb.ScriptErrorsSuppressed = true;
wb.Navigating += new WebBrowserNavigatingEventHandler(WebBrowser_Navigating);
wb.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(WebBrowser_DocumentCompleted);
wb.NewWindow += new CancelEventHandler(WebBrowser_NewWindow);
wb.ObjectForScripting = this;
try
{
TabPage currentTabPage = tabControls.SelectedTab;
//WebBrowser myWebBrowser = (WebBrowser)currentTabPage.Controls[0];
var myWebBrowser = (WebbrowserExt)sender;
strurl = myWebBrowser.Document.ActiveElement.GetAttribute("href");
if (string.IsNullOrEmpty(strurl))
strurl = myWebBrowser.BaseUrl;
if (string.IsNullOrEmpty(strurl))
strurl = myWebBrowser.StatusText;
if (!strurl.Contains("://"))
strurl = "http://" + strurl;
//刷新页面，不使用缓存设置
if (strurl.Contains("?"))
strurl = strurl + "&t=" + DateTime.Now.Ticks;
else
strurl = strurl + "?t=" + DateTime.Now.Ticks;

if (strurl.Contains(".exe"))
{ }
else
{

                wb.Navigate(strurl);
                e.Cancel = true;
                tabControls.TabPages.Add("新窗口" + SpaceString);
                tabControls.TabPages[tabControls.TabPages.Count - 1].Controls.Add(wb);

                wb.Dock = DockStyle.Fill;

                tabControls.SelectedIndex = tabControls.TabPages.Count - 1;
                //清除缓存
                CleanTempFiles();
            }
        }
        catch (Exception e2)
        {
        }
    }