private void initializeReservationComboBox()
        {
            reservationComboBoxInfos = new List <ReservationComboBoxInfo>();
            foreach (var reservation in ReservationCalendar.reservationCalendar)
            {
                if (reservation.borrowerId == CurrentlyLoggedUser.currentlyLoggedUserId)
                {
                    ReservationComboBoxInfo temp = new ReservationComboBoxInfo();
                    temp.carId      = reservation.carId;
                    temp.carName    = CarList.getSpecificCarName(reservation.carId);
                    temp.rentedFrom = reservation.rentedFrom;
                    temp.rentedTo   = reservation.rentedTo;

                    reservationComboBoxInfos.Add(temp);
                }
            }
        }
        private void DeleteButton_Click(object sender, RoutedEventArgs e)
        {
            ReservationComboBoxInfo temp = (ReservationComboBoxInfo)reservationsComboBox.SelectedItem;

            if (temp == null)
            {
                System.Windows.MessageBox.Show("Please select reservation.");
                return;
            }
            Reservation resToDelete = new Reservation(CurrentlyLoggedUser.currentlyLoggedUserId, temp.carId, temp.rentedFrom, temp.rentedTo);

            ReservationCalendar.deleteReservationFromList(resToDelete);

            System.Windows.MessageBox.Show("Reservation deleted!");
            User_ControlPanel user_ControlPanel = new User_ControlPanel(Left, Top);

            user_ControlPanel.Show();
            Close();
        }