Subclassing QGraphicsItemGroup

I have system that has classes derived from Q开发者_StackOverflowGraphicsWidget. I manage derived class objects in layouts on QGraphicsScene. Now I need a compound item that contain two or more QGraphicsWidget in it and also I need to put that item inside my layout. So I choose QGraphicsItemGroup and write I class like this.

class CompositeItem : public QGraphicsItemGroup,public QGraphicsLayoutItem
{   
   ...  
};

I only implemented sizeHint function again. When add CompositeItem instance to layout it does not shown. What may cause this? Where I made wrong?

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Call show() on either the QGraphicsItemGroup or QGraphicsWidgets after adding to the layout.

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Add setGraphicsItem( this ) to your constructor.