private void btnEdit_Click(object sender, RoutedEventArgs e)
 {
     if (dgKorisnik.SelectedItem != null)
     {
         DpKorisnik dpKorisnik = new DpKorisnik((Korisnik)dgKorisnik.SelectedItem);
         dpKorisnik.ShowDialog();
     }
 }
        private void btnAdd_Click(object sender, RoutedEventArgs e)
        {
            DpKorisnik dpKorisnik = new DpKorisnik();

            dpKorisnik.ShowDialog();
        }