private void AddPaymentSourceButton_Click(object sender, RoutedEventArgs e)
{
Payment p = MyWallet.Get(PaymentSourceDropdown.SelectedIndex);
double amount = double.Parse(PaymentAmountInput.Text);
Current.AddPayment(new PaymentLine(p, amount));
PaymentAmountInput.Text = "";
TotalFundsAmountLabel.Content = $"${Current.GetTotalFunds()}";
if (TransactionGrid.ItemsSource == null)
{
TransactionGrid.ItemsSource = Current.Items;
PaymentGrid.ItemsSource = Current.Payments;
}
}