我尝试获取父背景并将其设置为复选框的背景颜色。我有这样的绘制方法来绘制复选框：

void paint( QPainter* painter,
            const QStyleOptionViewItem& option,
            const QModelIndex &index) const
{
    // Get item data
    bool value = index.data(Qt::UserRole).toBool();
    QString text = index.data(Qt::DisplayRole).toString();

    // Fill style options with item data
    const QStyle *style = QApplication::style();
    QStyleOptionButton opt;
    opt.state |= value ? QStyle::State_On : QStyle::State_Off;
    opt.state |= QStyle::State_Enabled;
    opt.text = text;
    opt.rect = option.rect;

    // Draw item data as CheckBox
    style->drawControl(QStyle::CE_CheckBox,&opt,painter);
}

但如何设置此复选框的背景颜色呢？