private void buttonPromeni_Click(object sender, RoutedEventArgs e)
        {
            if (dataGridAerodromi.SelectedIndex == -1)
            {
                MessageBox.Show("Morate odabarti Aerodrom koji zelite da promenite");
                dataGridAerodromi.Focus();
                return;
            }
            Aerodrom           aerodrom = (Aerodrom)dataGridAerodromi.SelectedItem;
            Aerodrom           stari    = (Aerodrom)aerodrom.Clone();
            int                index    = VratiIndex(aerodrom);
            EditAerodromWindow ea       = new EditAerodromWindow(aerodrom, Stanje.Izmena);

            if (ea.ShowDialog() == false)
            {
                Aplikacija.Instance.Aerodromi[index] = stari;
            }
        }
        private void buttonDodaj_Click(object sender, RoutedEventArgs e)
        {
            EditAerodromWindow ea = new EditAerodromWindow(new Aerodrom(), Stanje.Dodavanje);

            ea.ShowDialog();
        }