QGraphicsItem child visibility

I have simple scene (QGraphicsScene) with custom item (QGraphicsItem)
the code but from my another question - http://stackoverflow.com/questions/2...lect-its-child
This problem is still unresolved but I want to ask another question:

If I click on item it shows his children.
If I click outside it hides all the children.
If I click again so children not get visible - I tested it with debugger, the code with child->setVisible() execuded but without result, children are still invisible.

What I do wrong?