QTreeWidget* MainWindow::createTreeWidget()
{
    auto  treeWidget = new QTreeWidget;
    treeWidget->setHeaderLabel("Items");
    treeWidget->setAlternatingRowColors(true);
    treeWidget->setSelectionMode(QAbstractItemView::ExtendedSelection);
    treeWidget->setSortingEnabled(true);
    for (int i = 1; i <= 100; ++i) {
        QTreeWidgetItem* item = new QTreeWidgetItem(treeWidget);
        item->setText(0, QString("Item %1").arg(i));
        item->setCheckState(0, Qt::Unchecked);
    }
    return treeWidget;
}