private void printAdapter_ValidateAppointments(object sender, AppointmentsValidationEventArgs e)
        {
            int count = e.Appointments.Count;
            AppointmentBaseCollection result = new AppointmentBaseCollection();

            for (int i = 0; i < count; i++)
            {
                Appointment apt = e.Appointments[i];
                if (apt.IsRecurring)
                {
                    result.Add(apt);
                }
            }
            e.Appointments.Clear();
            e.Appointments.AddRange(result);
        }
        void SchedulerAdapter_ValidateAppointments(object sender, AppointmentsValidationEventArgs e)
        {
            int count = e.Appointments.Count;
            AppointmentBaseCollection result = new AppointmentBaseCollection();

            for (int i = 0; i < count; i++)
            {
                Appointment apt = e.Appointments[i];
                // Add recurring appointments to the resulting collection
                if (apt.IsRecurring)
                {
                    result.Add(apt);
                }
            }
            e.Appointments.Clear();
            e.Appointments.AddRange(result);
        }