my function open a internet page in pop-up browser before to download a file. But after I change to SL4 and out-of-browser, seems the pop-up is no longer working
System.Windows.Browser.HtmlPage.PopupWindow(_uri, "Report", null);
and then I also tried HttpWebRequest and WebBrowser. Seems they both won't ask the user to download the file or not, but just stay silence.