private void Display(bool canShowObj)
 {
     MainViewModel mv = new MainViewModel();
     mv.AddGroup(canShowObj);
     if (selectedItemIndexes != null)
     {
         mv.AddGroup(selectedItemIndexes);
     }
     this.DataContext = mv;
 }
 public MainWindow()
 {
     InitializeComponent();
     MainViewModel mv = new MainViewModel();
     mv.AddGroup(true);
     this.DataContext = mv;
     pointList.ItemsSource = mv.Points;
     points = mv.Points;
     faces = mv.Faces;
     
 }