internal OpenFileDialogViewModel(OpenFileDialog dialog) : base(dialog)
        {
            Filter = dialog
                     .ObserveProperty(x => x.Filter)
                     .ToReadOnlyReactivePropertySlim()
                     .AddTo(disposable);

            CheckFileExists = dialog
                              .ObserveProperty(x => x.CheckFileExists)
                              .ToReadOnlyReactivePropertySlim()
                              .AddTo(disposable);

            FileName = dialog
                       .ToReactivePropertyAsSynchronized(x => x.FileName)
                       .AddTo(disposable);
        }