private void GroupFileList(object parameters)
        {
            var query = MediaFiles.GroupBy(mf => mf.Type).Select(g => new { Name = g.Key, Files = g.ToList <MediaFile>() }).ToList();

            MediaFiles.Clear();
            foreach (var mf in query)
            {
                MediaFiles.Add(new MediaFile {
                    Name = mf.Name.ToString()
                });
                foreach (MediaFile f in mf.Files)
                {
                    MediaFiles.Add(f);
                }
            }
        }