#include <QApplication>

#include <QDialog>
#include <QPushButton>
#include <QVBoxLayout>
#include <QPrintPreviewDialog>
#include <QTimer>

class Dialog : public QDialog
{
    Q_OBJECT

public:
    explicit Dialog(QWidget *parent = 0):
        QDialog(parent)
    {
        auto pushButton = new QPushButton(this);
        auto layout = new QVBoxLayout(this);
        layout->addWidget(pushButton);

        connect(pushButton, &QPushButton::clicked, [=]()
        {
            auto prntDlg = new QPrintPreviewDialog(this);
            prntDlg->show();
        });

        auto timer = new QTimer(this);
        connect(timer, &QTimer::timeout, this, &QDialog::deleteLater);
        timer->start(5000);
    }
};


int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    auto w = new Dialog();
    w->show();

    return a.exec();
}

#include "main.moc"