private void BtnAdd_Click(object sender, RoutedEventArgs e) { if (editMode) { ToggleEditMode(false); } if (addMode) { if (ValidateFields()) { fuelPurchases.Add( vehicle, decimal.Parse(tbCost.Text), double.Parse(tbLitres.Text), (DateTime)dpDate.SelectedDate ); changes = true; ToggleAddMode(false); Refresh(); } } else { ToggleAddMode(true); } }