Selects an item in QTreeView, press Ctrl key, the application will freezes

#include <QGridLayout>
#include <QStringListModel>
#include <QTreeView>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    auto model = new QStringListModel(this);
    QStringList list;
    list << "a" << "b" << "c"<< "a" << "b" << "c"<< "a" << "b" << "c";
    model->setStringList(list);

    auto tree = new QTreeView(this);
    tree->setModel(model);

    QGridLayout *mainLayout = new QGridLayout;
    mainLayout->setSpacing(0);
    mainLayout->setContentsMargins(0, 0, 0, 0);
    mainLayout->addWidget(tree);
    ui->centralwidget->setLayout(mainLayout);
}