// Methode
public void Add_PlaylistPart(PlaylistPart p)
{
liste.Add(p);
duree.Add(p.Get_Duree());
saved = false;
}
public void Swap_Parts(int i, int j)
{
PlaylistPart buf = liste[i];
liste[i] = liste[j];
liste[j] = buf;
saved = false;
}