public void SaveAsText()
 {
     try
     {
         var dialog = new FileDialogViewModel(FileDialogMode.Save);
         var res    = WindowManager.ShowDialog(dialog);
         if (res.HasValue && res.Value)
         {
             var text       = _repository.PresentAsText(Document, dialog.SourceType);
             var textViewer = new TextViewerViewModel(text, true, false, true);
             WindowManager.ShowDialog(textViewer);
         }
     }
     catch (Exception e)
     {
         ShowError(e);
     }
 }