fltkeep-command-usages.dart

// when pressed, dissmiss the bottom sheet and return a command
IconButton(
  icon: const Icon(Icons.archive),
  tooltip: 'Archive',
  onPressed: () => Navigator.pop(context, NoteStateUpdateCommand(
    id: _note.id,
    uid: uid,
    from: _note.state, // the current state
    to: NoteState.archived, // the transition target
  )),
),

// receiving a command
void _showNoteBottomSheet(BuildContext context) async {
  final command = await showModalBottomSheet<NoteCommand>(
    ...
  );

  if (command != null) {    
    processNoteCommand(_scaffoldKey.currentState, command);
  }
}

/// Processes the given [command], displays a SnackBar.
Future<void> processNoteCommand(ScaffoldState scaffoldState, NoteCommand command) async {
  await command.execute();
  final msg = command.message;
  if (mounted && msg?.isNotEmpty == true) {
    scaffoldState?.showSnackBar(SnackBar(
      content: Text(msg),
      action: SnackBarAction(
        label: 'Undo',
        onPressed: () => command.revert(),
      ),
    ));
  }
}