private void StopProgressOnCancel(SynchronizationContext sync, SendingProgressForm form)
        {
            SendOrPostCallback c = (state) =>
            {
                MessageBox.Show("Cancelled");
                form.Close();
            };

            sync.Post(c, null);
        }
        private void CompleteProgress(SynchronizationContext sync, SendingProgressForm form)
        {
            SendOrPostCallback c = (state) =>
            {
                form.To100();
                MessageBox.Show("Completed");
                form.Close();
            };

            sync.Post(c, null);
        }