private static Screenshot[] GetFiles(string filter) {
var directory = FileUtils.GetDocumentsScreensDirectory();
if (!Directory.Exists(directory)) return new Screenshot[0];
return new DirectoryInfo(directory).GetFiles(filter).Where(x => Filter.IsMatch(x.Name))
.OrderByDescending(x => x.CreationTime)
.Select(x => new Screenshot(x.FullName, x.CreationTime, x.Length)).ToArray();
}