/// <summary>
        /// Fill bill form
        /// </summary>
        private void fillBillForm()
        {
            tbBillNumber.Text      = selectedBill.BillNumber;
            tbReferenceNumber.Text = selectedBill.ReferenceNumber;
            tbReference.Text       = selectedBill.Reference;
            tbOverdueRate.Text     = selectedBill.OverdueRate;

            dueDate.SelectedDate  = selectedBill.DueDate;
            billDate.SelectedDate = selectedBill.BillDate;

            // Select customer (stupid way, but I don't have time to make it better)
            List <UI.ComboBoxItem> list = new List <UI.ComboBoxItem>();

            foreach (var item in cbCustomers.ItemsSource)
            {
                UI.ComboBoxItem it = (UI.ComboBoxItem)item;

                list.Add(it);
            }

            cbCustomers.SelectedItem = list.Where(x => x.Id == selectedBill.CustomerId).FirstOrDefault();

            // Fill bill rows
            dgBillRows.ItemsSource = selectedBill.BillRows;
        }
        /// <summary>
        /// Fill bill object
        /// </summary>
        /// <param name="bill"></param>
        /// <param name="action"></param>
        private void fillBillObject(ref Bill bill, Enums.Action action)
        {
            bill.BillNumber = tbBillNumber.Text;

            if (dueDate.SelectedDate != null)
            {
                bill.DueDate = DateTime.Parse(dueDate.SelectedDate.Value.ToShortDateString());
            }
            else
            {
                validationErrors.Add("- Laskulle pitää syöttää eräpäivä.");
            }

            if (billDate.SelectedDate != null)
            {
                bill.BillDate = DateTime.Parse(billDate.SelectedDate.Value.ToShortDateString());
            }
            else
            {
                validationErrors.Add("- Laskulle pitää syöttää laskutuspäivä.");
            }

            bill.ReferenceNumber = tbReferenceNumber.Text;
            bill.Reference       = tbReference.Text;
            bill.OverdueRate     = tbOverdueRate.Text;

            bill.BIC  = company.BIC;
            bill.IBAN = company.IBAN;

            // Get selected customer
            UI.ComboBoxItem item = (UI.ComboBoxItem)cbCustomers.SelectedItem;

            if (item != null)
            {
                bill.CustomerId = item.Id;
            }
            else
            {
                validationErrors.Add("- Laskulle pitää valita asiakas.");
            }

            // Bill rows
            bill.BillRows = dgBillRows.ItemsSource as List <BillRow>;
        }