private void SortirajDodatnuUslugu()
{
string orderHack = cbOrderHack.SelectedValue.ToString();
view = CollectionViewSource.GetDefaultView(DodatnaUsluga.Sort(cbSortiranje.SelectedItem.ToString(), orderHack));
dgNamestaj.ItemsSource = DodatnaUsluga.Sort((cbSortiranje.SelectedItem.ToString()), orderHack);
dgNamestaj.IsSynchronizedWithCurrentItem = true;
}