Qt5 显示窗口的Corner分配到DockWidget

    // specify how corner are occupied by the dockable widget
    window->setCorner(Qt::TopLeftCorner, Qt::LeftDockWidgetArea);
    window->setCorner(Qt::BottomLeftCorner, Qt::LeftDockWidgetArea);
    window->setCorner(Qt::TopRightCorner, Qt::RightDockWidgetArea);
    window->setCorner(Qt::BottomRightCorner, Qt::RightDockWidgetArea);