private void Filter()
        {
            //var total = new CityOverview();
            OverviewData.Clear();

            foreach (var city in m_Cache.Where(x => x.TotalTroops.TotalTS > 0))
            {
                if (CitiesWithoutCommandsOnly ?? false)
                {
                    if (city.TotalTroops.TotalTS != city.TroopsAtHome.TotalTS)
                    {
                        continue; //to pomijam bo coś tam robią :)
                    }
                }

                if (city.ContainsSearchExp(FilterTxt))
                {
                    if (string.IsNullOrWhiteSpace(FilterTxt))
                    {
                        city.GroupingDesc = "All cities";
                    }
                    else
                    {
                        city.GroupingDesc = "Row contains: " + FilterTxt;
                    }

                    OverviewData.Add(city);
                    //total.TroopsAtHome.Add(city.TroopsAtHome);
                    //total.TotalTroops.Add(city.TotalTroops);
                }
            }

            //total.GroupingDesc = "TOTAL";
            //total.TroopsAtHome.RecalcFields();
            //total.TotalTroops.RecalcFields();
            //OverviewData.Add(total);
        }