private void btnCreateNewDefinition_Click(object sender, RoutedEventArgs e) { var dialog = new CreateValue(); if (dialog.ShowDialog() == true) { if (!string.IsNullOrWhiteSpace(dialog.ResponseText)) { DataFac.AddProperty(new Property(dialog.ResponseText)); } else { MessageBox.Show("Du mangler at udfylde feltet"); } } FillOutProperty(); }