private void ListDown()
{
if (SelectedMusic == null)
{
return;
}
int index = MusicList.IndexOf(SelectedMusic);
if (index == MusicList.Count - 1)
{
return;
}
PlayerModel model = SelectedMusic.Clone() as PlayerModel;
MusicList.Remove(SelectedMusic);
MusicList.Insert(index + 1, model);
SelectedIndex = MusicList.IndexOf(model);
}