Inheritance: UIViewController, IUIViewControllerPreviewingDelegate
		protected virtual UINavigationController CreateDocumentsNavigationController (DocumentsViewController docList)
		{
			return new DocumentsNavigationController (docList);
		}
		async Task MoveDoc (IFile file, DocumentsViewController listC, IFileSystem dest, string destDir, bool animated)
		{
			await ActiveFileSystem.MoveAsync (file, dest, destDir);
			listC.RemoveDocuments (new[]{file.Path}, animated);
		}