How to receive notifications when a QList has been changed?

[grayfox]

Consider this code:

QMenuBar bar;
bar.actions().append(new QAction("Hello World"));

QMenuBar bar;
bar.actions().append(new QAction("Hello World"));

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QMenuBar returns a QList of QAction pointer, after I appended a new action, how does QMenuBar be notified on the change, so that it can update the UI accordingly?

I also tried to create a class that inherits from QList and I found no way to be notified when the list is changed.

Thanks in advance.