I\'d like to place QMainWindow instance inside another QWidget (for example centralWidget of another QMainWindow).
I\'m wondering why it doesn\'t work ? QMainWindow
QMainWindow provides predefined stuff like toolbars and status bars and menu bars in a platform agnostic way (it "does the right thing", without manual intervention). If all you need is a bunch of buttons in a layout, use QWidget.
You need to make sure each QMainWindow has centralQWidget`, other than that, you should be fine.