Draw figure underneath other figure

Hi, wrote the code and now i have problem. I would like next figures to be seen underneath the figures which have been already drawn. I wrote simple code below as example of the problem, line should be drawn underneath the rectangle:

Code:

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Window::Window(QWidget *parent) :
    QWidget(parent)
{
  setMinimumSize(400,400);
  setBackgroundRole(QPalette::Base);
  setAutoFillBackground(true);
}
 
void Window::paintEvent(QPaintEvent *){
  QPainter painter(this);
  painter.setBrush(QBrush(Qt::yellow));
  painter.drawRect(QRect(QPoint(100,100),QPoint(200,200)));
 
  painter.setCompositionMode(QPainter::CompositionMode_SourceOver);
 
  painter.setPen(QPen(Qt::red));
  painter.drawLine(QPointF(150,50),QPointF(150,300));
}

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