问如何更改QTableWidget的最小大小？

EN

#include "TableWidget.h"

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

    TableWidget *x1 = new TableWidget(2,2);
    for(int i = 0; i < x1->rowCount(); i++) {
        for(int j = 0; j < x1->columnCount(); j++) {
            x1->setCellWidget(i,j,new TableWidget(2,2));
        }
    }

    QGridLayout *layout = new QGridLayout;
    layout->addWidget(x1, 0, 0);

    QWidget *window = new QWidget;
    window->setLayout(layout);
    window->show();

    return a.exec();
}

class TableWidget : public QTableWidget
{
    Q_OBJECT
public:
    TableWidget(int rows, int columns, QWidget *parent = 0);
private:
signals:
public slots:
};

TableWidget::TableWidget(int rows, int columns, QWidget *parent) :
    QTableWidget(rows,columns,parent)
{
    //------
    QTableWidget::horizontalHeader()->hide();
    QTableWidget::verticalHeader()->hide();
    //------
    QTableWidget::horizontalHeader()->setResizeMode(QHeaderView::Stretch);
    QTableWidget::verticalHeader()->setResizeMode(QHeaderView::Stretch);
    //------
    QTableWidget::setEditTriggers(QAbstractItemView::NoEditTriggers);
    //------
    QTableWidget::setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    QTableWidget::setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    //------
    QTableWidget::horizontalHeader()->setMinimumSectionSize(1);
    QTableWidget::verticalHeader()->setMinimumSectionSize(1);
    QTableWidget::horizontalHeader()->setDefaultSectionSize(1);
    QTableWidget::verticalHeader()->setDefaultSectionSize(1);
    // FIXME, the minimum size is not 1 pixel... it is like 10 pixels...
    //------
    QTableWidget::setSelectionMode(QAbstractItemView::NoSelection);
}