有具体的代码嘛

当然可以给出一些示例代码来帮助您更好地理解：

1. 鼠标事件的实现：

void MyWidget::mousePressEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        m_dragging = true;
        m_dragPos = event->pos();
    }
}

void MyWidget::mouseMoveEvent(QMouseEvent *event)
{
    if (m_dragging) {
        QPoint newPos = event->pos();
        QPoint delta = newPos - m_dragPos;
        m_button->move(m_button->pos() + delta);
        m_dragPos = newPos;
        statusBar()->showMessage(QString("x=%1, y=%2").arg(m_button->x()).arg(m_button->y()));
    }
}

void MyWidget::mouseReleaseEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        m_dragging = false;
    }
}

2. 键盘事件的实现：

void MyWidget::keyPressEvent(QKeyEvent *event)
{
    if (event->key() == Qt::Key_M && event->modifiers() == Qt::ControlModifier) {
        showMaximized();
    }
}

3. 弹出式菜单的实现：

QMenu *menu = new QMenu(this);
QAction *maximizeAction = new QAction(QIcon(":/icons/maximize.png"), tr("最大"), this);
QAction *minimizeAction = new QAction(QIcon(":/icons/minimize.png"), tr("最小"), this);
QAction *normalAction = new QAction(QIcon(":/icons/normal.png"), tr("普通"), this);
menu->addAction(maximizeAction);
menu->addAction(minimizeAction);
menu->addAction(normalAction);
connect(maximizeAction, &QAction::triggered, this, &MyWidget::maximize);
connect(minimizeAction, &QAction::triggered, this, &MyWidget::minimize);
connect(normalAction, &QAction::triggered, this, &MyWidget::normal);
m_button->setContextMenuPolicy(Qt::CustomContextMenu);
connect(m_button, &QWidget::customContextMenuRequested, [=](const QPoint &pos){
    menu->exec(m_button->mapToGlobal(pos));
});

4. 工具栏的实现：

QToolBar *toolbar = new QToolBar(this);
toolbar->addAction(maximizeAction);
toolbar->addAction(minimizeAction);
toolbar->addAction(normalAction);
addToolBar(toolbar);

5. 双击事件的实现：

void MyWidget::mouseDoubleClickEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        showMaximized();
    } else if (event->button() == Qt::RightButton) {
        showNormal();
    }
}

这些代码仅供参考，具体实现过程还需要根据您的需求和布局进行适当修改。