private void btnIzmeniKur_Click(object sender, RoutedEventArgs e)
        {
            Kurs k = dgKursevi.SelectedItem as Kurs;
            KurseviEditWindow kew = new KurseviEditWindow(k, MOD.IZMENA);

            if (kew.ShowDialog() == true)
            {
            }
        }
        private void btnDodajKur_Click(object sender, RoutedEventArgs e)
        {
            Kurs k = new Kurs();
            KurseviEditWindow kew = new KurseviEditWindow(k);

            if (kew.ShowDialog() == true)
            {
            }
        }