public override void SourceInitialize ()
{
amazon_base_dir = System.IO.Path.Combine (Source.Volume.MountPoint, audio_folders[2]);
amazon_source = new AmazonMp3GroupSource (Source, "AmazonMP3", amazon_base_dir);
amazon_source.AutoHide = true;
ringtones_source = new RingtonesGroupSource (Source);
ringtones_source.AutoHide = true;
}