在QTableWidget中获得点击的行号
对于右键点击事件，这里用到的是Qt::CustomContextMenu方法，本例通过右点QTableWidget，显示下拉菜单，

//customContextMenuRequested(QPoint)信号是QWidget中唯一右键菜单点击的信号，该信号发出的条件是：widget的ContextMenuPolicy必须是Qt::CustomContextMenu，此时右键点击就会发出此信号。

ui->tableWidget->setContextMenuPolicy (Qt::CustomContextMenu);
connect(ui->tableWidget,SIGNAL(customContextMenuRequested(QPoint)),this,SLOT(show_menu(QPoint)));


void Widget::show_menu(const QPoint pos)
{
	//设置菜单选项
    QMenu *menu = new QMenu(ui->tableWidget);
    QAction *pnew = new QAction("第一项",ui->tableWidget);
    QAction *pnew1 = new QAction("第二项",ui->tableWidget);
    connect (pnew,SIGNAL(triggered()),this,SLOT(clickgoose()));
    connect (pnew1,SIGNAL(triggered()),this,SLOT(clickmms()));
    menu->addAction(pnew);
    menu->addAction(pnew1);
    menu->move (cursor ().pos ());
    menu->show ();
    //获得鼠标点击的x，y坐标点
    int x = pos.x ();
    int y = pos.y ();
    QModelIndex index = ui->tableWidget->indexAt (QPoint(x,y));
    int row  = index.row ();//获得QTableWidget列表点击的行数
}