private void OnLoad(object obj)
        {
            var filePath = FindFile("Wczytaj wyniki");

            if (filePath == String.Empty)
            {
                MessageBox.Show("Problem z wczytywaniem", "Błąd", MessageBoxButton.OK, MessageBoxImage.Error);
                return;
            }
            var resultsPersister = new ResultsPersister();

            try
            {
                List <Pair <string, double> > results;
                string methodName;
                resultsPersister.LoadResults(filePath, out results, out methodName);

                Results       = new ObservableCollection <Pair <string, double> >(results);
                MethodName    = methodName;
                ResultsLoaded = true;
            }
            catch (Exception)
            {
                MessageBox.Show("Problem z wczytywaniem", "Błąd", MessageBoxButton.OK, MessageBoxImage.Error);
            }
        }
        private void OnSave(object obj)
        {
            var filePath = FindFile("Zapisz wyniki");

            if (filePath == String.Empty)
            {
                MessageBox.Show("Problem z zapisem", "Błąd", MessageBoxButton.OK, MessageBoxImage.Error);
                return;
            }
            var resultsPersister = new ResultsPersister();

            try
            {
                resultsPersister.SaveResults(EvaluationResults.ToList(), SelectedEvaluator.ToString(), filePath);
            }
            catch (Exception)
            {
                MessageBox.Show("Problem z zapisem", "Błąd", MessageBoxButton.OK, MessageBoxImage.Error);
            }
        }