Z Value of GraphicsItem

Z value of each QGraphicsItem determines its stacking order of visibility in parent items.
It can be explicitly specified by setZValue( qrea z ) . Otherwise, it is decided by the order of being assigned to its parent through these two functions:

• QGraphicsItem::setParentItem ( QGraphicsItem * parent )
• QGraphicsItemGroup::addToGroup ( QGraphicsItem * item )