private void Gaps_In_Usage_Click(object sender, RoutedEventArgs e)
        {
            List <UsageBlock> usageBlockList = watcher.BreaksInContinousUsageForTimeFrame(startTime, startTime + TimeSpan.FromDays(1));
            string            msg            = UsageBlockListToString(usageBlockList);

            MessageBox.Show(msg, "Gaps in usage", MessageBoxButton.OK,
                            MessageBoxImage.Information, MessageBoxResult.OK, MessageBoxOptions.DefaultDesktopOnly);
        }