Choosing startup screen in Weston + Wayland

Hello everyone!
Does anyone have issues with the Wayland compositor? Here I have a Linux + Weston + Wayland machine with a small integrated LCD display (800x480) and an external HDMI monitor (1920x1080).
My goal is to programmatically select the screen on which showing a QFrame, but no matter what I do it appears on the main display. Here's an example of my attempts:

Code:

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bool Manager::StartOnScreen(int screenIdx)
{
    _desktopWidget = QApplication::desktop();
 
    //Check if requested screen is available
    if(screenIdx >= _desktopWidget->screenCount())
    {
        qDebug() << "Screen index out of range";
        return false;
    }
 
    QWidget* screen = _desktopWidget->screen(screenIdx);
    QFrame* mainFrame = new QFrame();
 
    //Set frame color
    if(screenIdx == 0)
        mainFrame->setStyleSheet("background-color:rgb(0, 0, 254);");
    else
        mainFrame->setStyleSheet("background-color:rgb(254, 0, 0);");
 
    int width = screen->geometry().width();
    int height = screen->geometry().height();
    int x = screen->geometry().x();
    int y = screen->geometry().y();
 
    qDebug() << "Screen config #" + QString::number(screenIdx) + ": position=" + QString::number(x) + "x" + QString::number(y) + " size=" +QString::number(width) + "x" + QString::number(height);
 
    //Set frame screen and geometry
    mainFrame->setGeometry(screen->geometry());
 
    //Show the frame (windowed)
    mainFrame->show();
 
    //Show the frame (fullscreen)
    //mainFrame->showFullScreen();
 
    //Try to move the frame with setScreen
    //mainFrame->windowHandle()->setScreen(qApp->screens().at(screenIdx));
 
    return true;
}

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