private void TabItem_GotFocus_1(object sender, RoutedEventArgs e)
 {
     _chartType = MainViewModel.ChartType.PolarScatter;
     UpdateModel();
 }
 private void TabItem_GotFocus(object sender, RoutedEventArgs e)
 {
     _chartType = MainViewModel.ChartType.ZoneComparison;
     UpdateModel();
 }