private static void OnViewClosing(object sender, CancelEventArgs e)
        {
            View = null;
            if (sender is CreateModelView view)
            {
                view.Closing -= OnViewClosing;
            }

            _logger.Info("Create Model ended.");
        }
        public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
        {
            try
            {
                _logger.Info("Create Model started.");

                var uiApp = commandData.Application;
                var uiDoc = uiApp.ActiveUIDocument;

                if (View != null)
                {
                    if (View.WindowState == WindowState.Minimized)
                    {
                        View.WindowState = WindowState.Normal;
                    }
                    View.Activate();

                    return(Result.Succeeded);
                }

                var m  = new CreateModelModel(uiDoc);
                var vm = new CreateModelViewModel(m, false);
                var v  = new CreateModelView
                {
                    DataContext = vm
                };

                View          = v;
                View.Closing += OnViewClosing;

                var unused = new WindowInteropHelper(v)
                {
                    Owner = Process.GetCurrentProcess().MainWindowHandle
                };

                v.Show();

                _logger.Info("Create Model ended.");

                return(Result.Succeeded);
            }
            catch (Exception e)
            {
                _logger.Fatal(e);

                return(Result.Failed);
            }
        }