public static bool? ShowDialog()
 {
     var vm = new DataContextChangedChildViewModel();
     var v = new DataContextChangedChildView();
     v.DataContext = vm;
     return vm.ShowDialogBox();
 }
        public static bool?ShowDialog()
        {
            var vm = new DataContextChangedChildViewModel();
            var v  = new DataContextChangedChildView();

            v.DataContext = vm;
            return(vm.ShowDialogBox());
        }