private void UpdateButtonLabel(ToggleButton btn)
        {
            int       iType = Convert.ToInt32(btn.Tag);
            QueueType type  = (QueueType)iType;

            if (btn.IsChecked == true)
            {
                uint iCount = _sys.GetUnprocessedItemsCount(type);
                //int iCount = _sys.Items.Count(i => i.Queue.Type == type && !i.Processed);

                string count = string.Format("({0})", iCount);
                if (!(btn.Content as string).Contains(count))
                {
                    btn.Content = string.Concat(BUTTON_LABELS[iType], SPACE_SEPARATOR, count);
                }
            }
            else
            {
                btn.Content = BUTTON_LABELS[iType];
            }
        }