QScrollArea

   QWidget *widget1 = new QWidget;

    QVBoxLayout *lay = new QVBoxLayout;

    lay->setSpacing(10);

    for (int i = 0;i < 20;i++)

    {

    QPushButton *pb = new QPushButton(QString::number(i));

    pb->setFixedSize(30,20);

    lay->addWidget(pb);

    }

    widget1->setLayout(lay);

    ui->scrollArea->setWidget(widget1);