I need a way for a QGraphicsRectItem to draw on top of its children. I have a item that contains several children items. At a specific height I need to draw a line over the child items.
Is there a way to implement a drawForeground in a QGraphicsItems similar to the drawForeground in QGraphicsScene?
If at all possible I would prefer to not have to draw the line for each child item.
I'm not entirely sure what you are trying to do but I suspect you will encounter a great deal of grief trying to fight the framework by trying to make a part of the parent draw over its child items. Perhaps you can add a top level child that is over the other child items covering a limited area, and renders the same content as the parent and includes the special overlay lines you want?
It might also suit your purpose to draw right over the scene from the graphics view.