Hey there! Let's tackle your dynamic menu bar issue step by step. I see you've got the basics of adding menu items down, but there are a couple of tweaks needed to make the triggered() signals work properly and handle those New_Window instances correctly.

1. Fix the Window Display & Memory Management First #

Your current code creates a New_Window for each menu item, but it never actually shows the window—plus, without proper parent/ownership handling, you'll run into memory leaks. Let's adjust that first:

QMenu *menu = this->menuBar()->addMenu("Chat Members"); 
for (int i = 0; i < vec.size(); ++i){ 
    QString name = vec.at(i); 
    QAction *act = menu->addAction(name); 
    // Set MainWindow as the parent to auto-manage memory
    New_Window* new_window = new New_Window(this);
    // Use a lambda for flexible signal handling (Qt5+ recommended)
    connect(act, &QAction::triggered, this, [new_window, name](){
        // Customize the window with the member's name
        new_window->setWindowTitle("Chat with " + name);
        new_window->show(); // Make the window visible when clicked
        // If you need to pass the name to New_Window's internal logic:
        // new_window->setupChatSession(name);
    });
}

2. Pass Menu Item Data to a Traditional Slot (If You Prefer) #

If you'd rather stick with a dedicated slot function instead of lambdas, you can store the member's name in the QAction itself and retrieve it later:

First, add a slot declaration to your MainWindow header:

private slots:
    void onChatMemberClicked();

Then implement the slot in mainwindow.cpp:

void MainWindow::onChatMemberClicked()
{
    // Get the action that triggered the slot
    QAction *clickedAction = qobject_cast<QAction*>(sender());
    if (!clickedAction) return;

    // Retrieve the stored member name
    QString memberName = clickedAction->data().toString();
    
    // Create and show the window
    New_Window* new_window = new New_Window(this);
    new_window->setWindowTitle("Chat with " + memberName);
    new_window->show();
}

Update your menu creation code to attach the data:

QMenu *menu = this->menuBar()->addMenu("Chat Members"); 
for (int i = 0; i < vec.size(); ++i){ 
    QString name = vec.at(i); 
    QAction *act = menu->addAction(name); 
    act->setData(name); // Store the member name in the action
    connect(act, &QAction::triggered, this, &MainWindow::onChatMemberClicked);
}

3. Avoid Common Pitfalls #

• Prevent duplicate windows: If you don't want users opening multiple windows for the same chat member, use a QMap to track existing windows:

  // Add this as a member variable in MainWindow: QMap<QString, New_Window*> m_chatWindows;
  QMenu *menu = this->menuBar()->addMenu("Chat Members"); 
  for (int i = 0; i < vec.size(); ++i){ 
      QString name = vec.at(i); 
      QAction *act = menu->addAction(name); 
      connect(act, &QAction::triggered, this, [this, name](){
          if (m_chatWindows.contains(name)) {
              m_chatWindows[name]->activateWindow(); // Bring existing window to front
          } else {
              New_Window* new_window = new New_Window(this);
              new_window->setWindowTitle("Chat with " + name);
              new_window->setAttribute(Qt::WA_DeleteOnClose); // Auto-delete when closed
              // Remove from map when window is destroyed
              connect(new_window, &New_Window::destroyed, this, [this, name](){
                  m_chatWindows.remove(name);
              });
              m_chatWindows[name] = new_window;
              new_window->show();
          }
      });
  }
  

• Clean up memory: Always set a parent for dynamic windows or use Qt::WA_DeleteOnClose to avoid memory leaks.

内容的提问来源于stack exchange，提问作者cretos