I have created a small example project which you can use to replicate this issue and I attached it to this ticket.

When I set the animated flag of QMainWindow to false DockWidgets will prevent mouse events to work properly.

When you open this app, undock the dock widget and dock it back! Then the mainWindow's menu-bar will not work anymore. In fact all mouse events won't work anymore for this mainWindow.

#include "mainwindow.h"
#include "./ui_mainwindow.h"
#include <qdockwidget.h>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    setAnimated(false);
    QDockWidget *dockWidget = new QDockWidget(this);
    dockWidget->setMinimumWidth(200);
    addDockWidget(Qt::RightDockWidgetArea, dockWidget);
}

MainWindow::~MainWindow()
{
    delete ui;
}
 

I did test this behaviour under windows => under windows this works fine

I am setting animated to false, because in my project i have a slow centralWidget.