private TimeSpan?GetTimeBudget()
        {
            TimeSpan?budget              = null;
            double   timeNumber          = 0.0;
            var      correctedTimeBudget = TimeBudget.Replace('.', ',');

            if (double.TryParse(correctedTimeBudget, out timeNumber))
            {
                var selectedUnit = SelectedTimeBudgetUnit.FromReadableString();
                if (selectedUnit == TimeBudgetUnit.Hours)
                {
                    budget = TimeSpan.FromHours(timeNumber);
                }
                else if (selectedUnit == TimeBudgetUnit.ManDays)
                {
                    budget = TimeSpan.FromHours(timeNumber * 8);
                }
                else if (selectedUnit == TimeBudgetUnit.ManMonths)
                {
                    budget = TimeSpan.FromHours(timeNumber * 8 * 20);
                }
            }
            return(budget);
        }