private static void StopFilling(CarPictureBox car, FuelDispenserView fuelDispenser) { var carView = car.Tag as CarView; if (carView.FuelRemained > carView.TankVolume) { carView.FuelRemained = carView.TankVolume; var fuelSurplus = carView.FuelRemained - carView.TankVolume; fuelDispenser.ReturnFuelToTank(fuelSurplus); } car.IsFilling = false; car.IsFilled = true; fuelDispenser.CarsInQueue--; fuelDispenser.IsBusy = false; }