#include <QApplication>

#include <QTimer>
#include <QMenuBar>
#include <QMdiArea>
#include <QMdiSubWindow>
#include <QMainWindow>

#include <QtCharts/QChartView>

QT_CHARTS_USE_NAMESPACE

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QMainWindow mw;

    // Must have QMenuBar to see the problem
    // QMdiSubWindow maximizes differently when the menu bar is present
    mw.setMenuBar(new QMenuBar);

    QMdiArea mdi;
    mw.setCentralWidget(&mdi);

    // Can only reproduce the issue using a QChartView
    // Even QGraphicsView didn't have the issue.
    // Also, MDI area can only have one subwindow
    QChartView cv;
    QMdiSubWindow *sw = mdi.addSubWindow(&cv);

    QTimer::singleShot(1000, sw, &QMdiSubWindow::showMaximized);    // Maximize the SubWindow
    QTimer::singleShot(2000, sw, &QMdiSubWindow::showNormal);       // Take it back to normal
    QTimer::singleShot(3000, &mw, [&mw] {
        mw.hide();                                                  // Hide the MainWindow
        mw.grab();                                                  // This has to be done after hide()
        QTimer::singleShot(0, &mw, &QMainWindow::show);             // Must call show() from the event loop
    });

    // Repainting the Window and the viewport of the QChartView causes the window to re-appear
    QTimer::singleShot(5000, sw, SLOT(repaint()));
    QTimer::singleShot(5000, cv.viewport(), SLOT(repaint()));

    mw.show();
    return a.exec();
}