Given the following main window implementation:

#include <QApplication>

#include "MainWindow.h"

namespace ui {
MainWindow::MainWindow(QWidget *parent) :
        QMainWindow(parent),
        child(this) {
    this->resize(425, 450);
    this->child.move(10, 10);
    this->child.resize(400, 400);
}

MainWindow::~MainWindow() {}

void MainWindow::showEvent(QShowEvent* event) {
    QWidget::showEvent(event);

    qDebug() << "Updating.";
    this->child.update();
    this->child.update();
    this->child.update();
    this->child.update();
    this->child.repaint();
    this->child.repaint();
    this->child.repaint();
    this->child.repaint();
    QApplication::processEvents();
} 
}  // namespace ui

and the widget which looks like this:

#include <QPainter>

#include "Widget.h"

namespace ui {
Widget::Widget(QWidget *parent) :
        QWidget(parent) { }

void Widget::paintEvent(QPaintEvent *event) {
    qDebug() << "paintEvent called.";
    QWidget::paintEvent(event);
}
}  // namespace ui

I would expect to see at least four (and possibly more than eight) “paintEvent called.” messages in the console. However, the console just shows:

Updating.
paintEvent called.
paintEvent called.

The output is exactly the same if I remove all the this->child.update() and this->child.repaint() calls in MainWindow.cpp.

If update() and repaint() don’t actually update or repaint a widget, what should I do instead in order to force a redraw of a widget?