//Tworzenie nowego konta.
private void button_Click(object sender, RoutedEventArgs e)
{
account acc_add = new account();
acc_add.acc_nr = int.Parse(acc_nr_text.Text);
acc_add.owner = owner_text.Text;
acc_add.currency = combo_curr.Text;
acc_add.interest_type = double.Parse(interest_text.Text);
acc_add.balance = Math.Round(double.Parse(balance_text.Text), 2);
mw.account_list.Add(acc_add);
mw.save_acc_list();
MessageBox.Show("Stworzono konto o numerze: " + acc_add.acc_nr + "\nWłaściciel: " + acc_add.owner);
this.Close();
}