QDockWidget's height is reduced

1.QMainWindow has 3 QDockWidgets（A、B、C），QDockWidget's DockWidgetArea is Qt::LeftDockWidgetArea

2.The orientations of A and B are Qt::Vertical， the orientations of C and AB are Qt::Horizontal

3.QMainWindow has a QAction，the QAction calls

   A->setFixedWidth(A->width());

   B->setVisible(true or false);

   A->setMinimumSize(0, 0);

   A->setMaximumSize(QWIDGETSIZE_MAX, QWIDGETSIZE_MAX);

 

Actual result:  each time B DockWidget, it hides and displays a cycle, and the height of B decreases by 2 pixels.

 
Expected result: the height of B will not change.

 

Code：

// ui is a QMainWindow, the QMainWindow has a QMenuBar

ui.setupUi(this);
QAction* pAction = ui.mainToolBar->addAction("hide dock2");
connect(pAction, &QAction::triggered, [&]()

{ m_pDock1->setFixedWidth(m_pDock1->width()); m_pDock2->setVisible(!m_pDock2->isVisible()); m_pDock1->setMinimumSize(0, 0); m_pDock1->setMaximumSize(QWIDGETSIZE_MAX, QWIDGETSIZE_MAX); }

);

m_pDock1 = new QDockWidget("1", this);
m_pDock1->setWidget(new QLabel("hello"));
m_pDock2 = new QDockWidget("2", this);
m_pDock2->setWidget(new QLabel("world"));
m_pDock3 = new QDockWidget("3", this);
m_pDock3->setWidget(new QLabel("test"));
addDockWidget(Qt::LeftDockWidgetArea, m_pDock1, Qt::Horizontal);
addDockWidget(Qt::LeftDockWidgetArea, m_pDock2, Qt::Vertical);
addDockWidget(Qt::LeftDockWidgetArea, m_pDock3, Qt::Horizontal);