internal static async void Upload(ListItem listItem, HtmlCollection <File> files) { for (int i = 0; i < files.Length; i++) { if (!await LazyWindow.ShowWaiting(string.Format("{0}: uploading...", files[i].Name), delegate(CancellationToken cancellationToken) { return(listItem.AddAttachment(UriUtility.GetFileName(files[i].Name), files[i], cancellationToken)); })) { break; } } }