Евгений

StatefulBuilder(builder: (context, myState) {
                    return ElevatedButton(
                      onPressed: () {
                        myState(() {
                          _active = !_active;
                        });
                      },
                      child: Text('Work'),
                      style: ButtonStyle(
                          backgroundColor: MaterialStateProperty.all(
                              _active ? Colors.blue : Colors.red)),
                    );
                  }),