I am getting a run-time message

QObject: Cannot create children for a parent that is in a different thread.

when starting a QProcess in a std::thread. The program runs, but I feel that this message will be trouble, eventually.

I saw this one and this other answers (as well as some in python), which I did not see how to apply to my code.

I am using QtCreator, Qt 6.5 LTS and gcc 11.2.0 in Win10. A minimal working example is below. You will have to create an empty GUI window with QPushButton pushButton. The class definition is:

class MainWindow : public QMainWindow
{
  Q_OBJECT
    
public:
  MainWindow(QWidget *parent = nullptr);
  ~MainWindow();
    
private slots:
  void clicked(bool);
    
private:
  Ui::MainWindow *ui;
    
  void launchNotepad();
   
  std::thread th;
  QProcess process;
};

And the implementation is:

MainWindow::MainWindow(QWidget *parent)
  : QMainWindow(parent)
  , ui(new Ui::MainWindow)
{
  ui->setupUi(this);
  connect(ui->pushButton, SIGNAL(clicked(bool)), this, SLOT(clicked(bool)));
}

MainWindow::~MainWindow()
{
  delete ui;
}

void MainWindow::clicked(bool)
{
  th = std::thread{&MainWindow::launchNotepad,this};
  th.detach();
}

void MainWindow::launchNotepad()
{
  process.start("notepad");
}

When I click on the button, notepad indeed appears and all looks well. But the Application output console in QtCreator gives me the message “Cannot create children…”. For reasons beyond this question, I do want to work with std::thread.

My questions:

1. What is the trouble that I am sure eventually I’ll have because of this message ?

2. How to get rid of it, while keeping using std::thread ?