Yes it makes sense or I am doing sth else wrong, because my layout is not visible as a whole even if the size I give the rectangle and the size I give the layout are the same. I am not setting the layout as parent of my class. Maybe that leads to my problem:

class MyWindow : public TopWindow
{
    // Menu bar is added here...
}

GUI_APP_MAIN
{
    MyWindow app;
    app.SetRect(0, 0, 300, 150);

    WithMyLayout<TopWindow> layout;
    SetLayout_MyLayout(app, layout, true, true);

    app.Run();
}