Qt childForm menu в панель меню MDI

Question

У меня есть приложение MDI, mainWindow с QMDIArea. Форма содержит обычные меню (Система, Параметры, Окно, Справка). Я открываю childWindow (также класс MainWindow) как подокно с меню (например, formInvoice имеет меню Invoice и действия new, edit, save ...). Мне нужно связать меню childForm с меню mainForm MDI, ie Система, Счет, Параметры ... Либо автоматически (я не знаю, как), либо когда активирована одна из дочерних форм, загрузите список действий и вставьте их вручную в родительское меню главного окна MDI. Как это сделать?

Вот как это ведет себя (Qt 5.14):

Меню MDI

MDI -> открытая childForm

Мне нужно это:

MDI -> открытый childForm

Код:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QMdiSubWindow>
#include <QDebug>alt tex
#include "companies.h"
#include "invoices.h"

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
  Q_OBJECT

public:
  MainWindow(QWidget *parent = nullptr);
  ~MainWindow();

private slots:
  void on_actionCompaniesTriggered();
  void on_actionInvoicesTriggered();
  void on_mdiArea_subWindowActivated(QMdiSubWindow *arg1);
  void on_actionClose_triggered();

private:
  Ui::MainWindow *ui;
  void loadSubWindow(QMainWindow *mainSubWindow);
};
#endif // MAINWINDOW_H

#ifndef INVOICES_H
#define INVOICES_H

#include <QMainWindow>
#include <QAction>
#include <QMenu>
#include <QDebug>

namespace Ui {
  class Invoices;
}

class Invoices : public QMainWindow
{
  Q_OBJECT

public:
  explicit Invoices(QWidget *parent = nullptr);
  ~Invoices();

private slots:
  void on_actionNewTriggered();
  void on_actionEditTriggered();
  void on_actionSaveTriggered();
  void on_actionDeleteTriggered();
  void on_actionCloseTriggered();

private:
  Ui::Invoices *ui;
  QAction *action_new;
  QAction *action_edit;
  QAction *action_save;
  QAction *action_delete;
  QAction *action_close;

  QMenu *menuInvoices;
  void createActions();
};

#endif // INVOICES_H

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
  : QMainWindow(parent)
  , ui(new Ui::MainWindow)
{
  ui->setupUi(this);
  connect(ui->actionCompanies, SIGNAL(triggered()), this, SLOT(on_actionCompaniesTriggered()));
  connect(ui->actionInvoices, SIGNAL(triggered()), this, SLOT(on_actionInvoicesTriggered()));
}

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

void MainWindow::on_actionCompaniesTriggered(){
  loadSubWindow(new Companies(this));
}

void MainWindow::on_actionInvoicesTriggered(){
  loadSubWindow(new Invoices(this));
}

void MainWindow::loadSubWindow(QMainWindow *mainSubWindow){
  auto subWindow = ui->mdiArea->addSubWindow(mainSubWindow);
  subWindow->setAttribute(Qt::WA_DeleteOnClose);
  subWindow->setWindowTitle(mainSubWindow->windowTitle());
  subWindow->setWindowIcon(mainSubWindow->windowIcon());
  subWindow->setWindowState(Qt::WindowMaximized);
  subWindow->show();
}

void MainWindow::on_mdiArea_subWindowActivated(QMdiSubWindow *arg1)
{
    qDebug() << arg1->windowTitle();
}

void MainWindow::on_actionClose_triggered()
{
    close();
}

#include "invoices.h"
#include "ui_invoices.h"

Invoices::Invoices(QWidget *parent) :
  QMainWindow(parent),
  ui(new Ui::Invoices)
{
  ui->setupUi(this);
  createActions();
}

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

void Invoices::on_actionNewTriggered(){
  qDebug() << "actNew";
}

void Invoices::on_actionEditTriggered(){
  qDebug() << "actEdit";
}

void Invoices::on_actionSaveTriggered(){
  qDebug() << "actSave";
}

void Invoices::on_actionDeleteTriggered(){
  qDebug() << "actDelete";
}

void Invoices::on_actionCloseTriggered(){
  this->close();
}

void Invoices::createActions(){
  action_new = new QAction("&New", this);
  action_edit = new QAction("&Edit", this);
  action_save = new QAction("&Save", this);
  action_delete = new QAction("&Delete", this);
  action_close = new QAction("&Close", this);
  connect(action_close, SIGNAL(triggered()), this, SLOT(on_actionCloseTriggered()));
  connect(action_new, SIGNAL(triggered()), this, SLOT(on_actionNewTriggered()));
  connect(action_edit, SIGNAL(triggered()), this, SLOT(on_actionEditTriggered()));
  connect(action_save, SIGNAL(triggered()), this, SLOT(on_actionSaveTriggered()));
  connect(action_delete, SIGNAL(triggered()), this, SLOT(on_actionDeleteTriggered()));

  menuInvoices = new QMenu("Invoices", this);
  menuInvoices->addAction(action_new);
  menuInvoices->addAction(action_edit);
  menuInvoices->addAction(action_save);
  menuInvoices->addAction(action_delete);
  menuInvoices->addAction(action_close);
  ui->menubar->addMenu(menuInvoices);
}

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>800</width>
    <height>600</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <layout class="QVBoxLayout" name="verticalLayout">
    <item>
     <widget class="QMdiArea" name="mdiArea"/>
    </item>
   </layout>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>800</width>
     <height>22</height>
    </rect>
   </property>
   <widget class="QMenu" name="menuSystem">
    <property name="title">
     <string>System</string>
    </property>
    <addaction name="actionCompanies"/>
    <addaction name="actionInvoices"/>
    <addaction name="actionClose"/>
    <addaction name="actionAddMenu"/>
   </widget>
   <widget class="QMenu" name="menuOptions">
    <property name="title">
     <string>Options</string>
    </property>
   </widget>
   <widget class="QMenu" name="menuWindow">
    <property name="title">
     <string>Window</string>
    </property>
   </widget>
   <widget class="QMenu" name="menuHelp">
    <property name="title">
     <string>Help</string>
    </property>
   </widget>
   <widget class="QMenu" name="menuInvoices">
    <property name="title">
     <string>Invoices</string>
    </property>
   </widget>
   <addaction name="menuSystem"/>
   <addaction name="menuInvoices"/>
   <addaction name="menuOptions"/>
   <addaction name="menuWindow"/>
   <addaction name="menuHelp"/>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
  <action name="actionCompanies">
   <property name="text">
    <string>Companies</string>
   </property>
  </action>
  <action name="actionClose">
   <property name="text">
    <string>Close</string>
   </property>
  </action>
  <action name="actionInvoices">
   <property name="text">
    <string>Invoices</string>
   </property>
  </action>
 </widget>
 <resources/>
 <connections/>
</ui>

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>Invoices</class>
 <widget class="QMainWindow" name="Invoices">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>800</width>
    <height>600</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>Invoices</string>
  </property>
  <widget class="QWidget" name="centralwidget"/>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>800</width>
     <height>22</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>