备注：内容仅提供参考。

⒈添加引用：using Gecko;

⒉然后根据自己的情况在某个方法内添加事件：

        LauncherDialog.Download += new EventHandler<LauncherDialogEvent>(OnDownloadFile);

⒊再声明方法：

private void OnDownloadFile(objectsender, LauncherDialogEvent e){nsILocalFile objTarget= Xpcom.CreateInstance<nsILocalFile>("@mozilla.org/file/local;1");using (nsAString tmp = new nsAString(@Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) + "\temp.tmp")){objTarget.InitWithPath(tmp);}//Save file dialog
Stream myStream;System.Windows.Forms.SaveFileDialog saveFileDialog1= newSystem.Windows.Forms.SaveFileDialog();saveFileDialog1.Filter= "All files (*.*)|*.*";saveFileDialog1.FilterIndex= 2;saveFileDialog1.RestoreDirectory= true;saveFileDialog1.FileName=e.Filename;if (saveFileDialog1.ShowDialog() ==System.Windows.Forms.DialogResult.OK){if ((myStream = saveFileDialog1.OpenFile()) != null){nsIURI source=IOService.CreateNsIUri(e.Url);nsIURI dest= IOService.CreateNsIUri(newUri(@saveFileDialog1.FileName).AbsoluteUri);nsAStringBase t= (nsAStringBase)newnsAString(System.IO.Path.GetFileName(@saveFileDialog1.FileName));nsIWebBrowserPersist persist= Xpcom.CreateInstance<nsIWebBrowserPersist>("@mozilla.org/embedding/browser/nsWebBrowserPersist;1");persist.SaveURI(source,null, null, null, null, (nsISupports)dest, null);nsIDownloadManager DownloadMan= null;DownloadMan= Xpcom.CreateInstance<nsIDownloadManager>("@mozilla.org/download-manager;1");nsIDownload download= DownloadMan.AddDownload(0, source, dest, t, e.Mime, 0, null, (nsICancelable)persist, false);if (download != null){persist.SetPersistFlagsAttribute(2 | 32 | 16384);persist.SetProgressListenerAttribute((nsIWebProgressListener)download);persist.SaveURI(source,null, null, null, null, (nsISupports)dest, null);}myStream.Close();}}}