public PersonViewModelEventArgs(PersonViewModel person = null)
 {
     this.Person = person;
     Index = -1;
 }
 public PersonViewModelEventArgs(PersonViewModel person, int index)
 {
     this.Person = person;
     Index = index;
 }
 public AddNewPersonDialog()
 {
     TempPerson = new PersonViewModel(new Gast());
     DataContext = this;
     InitializeComponent();
 }