#include <qguiapplication.h>
#include <qquickwindow.h>
#include <qpainter.h>
#include <qquickpainteditem.h>

class RedRectangle : public QQuickPaintedItem
{
public:
    RedRectangle(QQuickItem *parent = nullptr) : QQuickPaintedItem(parent) {}

    void paint(QPainter *painter) override
    {
        painter->fillRect(boundingRect(), Qt::red);
    }
};

void init_window(QQuickWindow* window)
{
    RedRectangle* rect = new RedRectangle();
    rect->setParentItem(window->contentItem());
    rect->setWidth (100);
    rect->setHeight(100);
    
    window->show();
}

int main(int argc, char* argv[])
{
    QGuiApplication app(argc, argv);
    
    QQuickWindow window_0{};
    init_window(&window_0);
    
    // Both lines commented out for first example
    QQuickWindow window_1{};
    init_window(&window_1);
    
    return QGuiApplication::exec();
}