ui->menuPlugins->addAction(dockedWidget->toggleViewAction());

void MainWindow::addToPluginsMenu(QWidget *const widget) {
    ui->menuPlugins->setEnabled(true);
    QWidgetAction *ac = new QWidgetAction(this);
    ui->menuPlugins->addAction(ac);
}

// Create menu
QMenu * poMainMenu = new QMenu(this);

// toggled widget
QCheckBox * poCbTest = new QCheckBox("toggle",this);

// set the toggle widget as menu action
QWidgetAction *ac = new QWidgetAction(this);
ac->setDefaultWidget(poCbTest);

// add the action to the menu
poMainMenu->addAction(ac);