Qt. QStackedLayout does not work

我有一个用c++编写的控制台游戏，因为我目前正在尝试学习Qt，所以我决定将GUI添加到这个程序中作为练习。所以有一个名为"gui"的主窗口继承了Qwidget。它有布局QHBoxLayout* main_h_lo。它有2个额外的布局:1。qstackkedlayout * leftpart, 2。QGridLayout *甲板上。第一个是菜单部分。它有4个不同的小部件和它们的布局。例如选择游戏模式或打印游戏分数。第二种布局——甲板——是游戏桌，类似于棋盘。这里的构造函数代码包含了这个问题:

gui::gui(QWidget *parent) :
    QWidget(parent), pgame(nullptr)
{
    QHBoxLayout* main_h_lo = new QHBoxLayout;
    main_h_lo->setMargin(0);
    main_h_lo->setSpacing(0);
    setLayout(main_h_lo);
    //leftpart-widgets initialization:
    bot_or_playerW = new QWidget;
    QVBoxLayout* bot_or_playerL = new QVBoxLayout; 
    bot_or_playerL->addWidget(new QLabel("Choose game mode"));
    QPushButton* qpb1 = new QPushButton("vs Human");
    QPushButton* qpb2 = new QPushButton("vs Bot");
    QObject::connect(qpb1, SIGNAL(clicked()), SLOT(pvp()));
    QObject::connect(qpb2, SIGNAL(clicked()), SLOT(pvb()));
    bot_or_playerL->addWidget(qpb1);
    bot_or_playerL->addWidget(qpb2);
    bot_or_playerW->setLayout(bot_or_playerL);
    choosing_colourW = new QWidget;
    QVBoxLayout* choosing_colourL = new QVBoxLayout; 
    choosing_colourL->addWidget(new QLabel("Choose your colour"));
    QPushButton* qpb3 = new QPushButton("white(2nd turn)");
    QPushButton* qpb4 = new QPushButton("black(1st turn)");
    QObject::connect(qpb3, SIGNAL(clicked()), SLOT(chwh()));
    QObject::connect(qpb4, SIGNAL(clicked()), SLOT(chbl()));
    choosing_colourL->addWidget(qpb3);
    choosing_colourL->addWidget(qpb4);
    choosing_colourW->setLayout(bot_or_playerL);
    score_lturnW = new QWidget;
    QVBoxLayout* score_lturnL = new QVBoxLayout; 
    lturn = new QLabel; 
    pturn = new QLabel;
    score = new QLabel;
    score_lturnL->addWidget(lturn);
    score_lturnL->addWidget(pturn);
    score_lturnL->addWidget(score);
    score_lturnW->setLayout(score_lturnL);
    after_gameW = new QWidget;
    QVBoxLayout* after_gameL = new QVBoxLayout; 
    winner = new QLabel;
    offer_to_play_again = new QLabel("Wanna play again?");
    QPushButton* qpb5 = new QPushButton("yes");
    QObject::connect(qpb5, SIGNAL(clicked()), SLOT(restart()));
    QPushButton* qpb6 = new QPushButton("no");
    QObject::connect(qpb6, SIGNAL(clicked()), qApp, SLOT(quit()));
    after_gameW->setLayout(after_gameL);
    leftpart = new QStackedLayout;
    leftpart->addWidget(bot_or_playerW);
    leftpart->addWidget(choosing_colourW);
    leftpart->addWidget(score_lturnW);
    leftpart->addWidget(after_gameW);
    //"rightpart" init:
    deck = new QGridLayout;
    deck->setMargin(0);
    deck->setSpacing(0);
    e_pic = QPixmap("empty.png");
    b_pic = QPixmap("black.png");
    w_pic = QPixmap("white.png");
    pic_sz = e_pic.size();
    for (int i = 0; i < 8; ++i)
        for (int j = 0; j < 8; ++j)
        {
            QPushButton* tqpb = new QPushButton;
            tqpb->setIcon(e_pic);
            tqpb->setIconSize(pic_sz);
            std::stringstream ss;
            std::string s;
            ss << i << j;
            ss >> s;
            tqpb->setObjectName(s.c_str());
            deck->addWidget(tqpb, i, j);
            connect(tqpb, SIGNAL(clicked()), SLOT(turn_try()));
        }
    main_h_lo->addLayout(leftpart);
    main_h_lo->addLayout(deck);
    leftpart->setCurrentWidget(bot_or_playerW);
}

我没有得到错误或警告。甲板部分是可怕和丑陋的，但它是预期的:D。"菜单"部分没有显示出来——这就是问题所在。屏幕:https://i.stack.imgur.com/WOMx3.jpg .