All right, fixed

I needed to set autoFillBackground to false. I did that, but I did it using the QGraphicsView::setupViewport(..)-method. Unfortunately, it's not emitted after setting a new viewport in my Qt-snapshot from 18/01/08, while it should be according to the documentation. So that means the autoFillBackground was still on, even though I told it to be off.

That's my fault for wanting to be on the bleeding edge, I guess