效果：

关键代码：

1、删除主窗口，使用QDockWidget替代主窗口

		QWidget* p = takeCentralWidget();
		if (p)
			delete p;

		setDockNestingEnabled(true);
		centralWidget = new QDockWidget(this);
		centralWidget->setAllowedAreas(Qt::AllDockWidgetAreas);
		setCentralWidget(centralWidget);

2、禁止QDockWidget之间互相tab叠加：

//取消AllowTabbedDocks
setDockOptions(QMainWindow::AnimatedDocks);

3、动态插入，根据数量决定初次摆放的位置

Qt::DockWidgetArea area_ = Qt::LeftDockWidgetArea;
		if (dockWidgets.size() % 4 == 0)
			area_ = Qt::LeftDockWidgetArea;
		else if (dockWidgets.size() % 4 == 1)
			area_ = Qt::RightDockWidgetArea;
		else if (dockWidgets.size() % 4 == 2)
			area_ = Qt::TopDockWidgetArea;
		else if (dockWidgets.size() % 4 == 3)
			area_ = Qt::BottomDockWidgetArea;

		QDockWidget *dockWidget = new QDockWidget(this);
		dockWidget->setAllowedAreas(Qt::AllDockWidgetAreas);
		OneSensorRealtimeViewWindow* dockWidgetContents = new OneSensorRealtimeViewWindow();
		dockWidget->setWidget(dockWidgetContents);
		dockWidget->setWindowTitle(tr("SN:") + sn + tr(" address:") + add);
		this->addDockWidget(area_, dockWidget);

4、当窗口被关闭或者拖动到外部时，进行复位

	QDockWidget * last_ = nullptr;
	QMapIterator<QString, QDockWidget *> i(dockWidgets);
	while (i.hasNext()) {
		i.next();

		if (i.value() != nullptr)
		{
			i.value()->show();
			i.value()->setFloating(false);
		}
	}