title: How to use Qt C++ controls in Qml?
body: <p>UI of my application is implemented in QML. It has a large nested menu with many items in many levels of hierarchy. This menu implemented in QML. Filling and updating of this menu take several seconds. It is too slow. I want to implement this menu in C++. 
  I know how to implement simple QML control in C++: I should extend class QQuickPaintedItem.
  But the menu is not such a simple class. It contains children.</p>
  
  <p>How to implement the menu for QML in C++? Can I use QMenu C++ class in QML?</p>