Displaying bug with QGraphicsView in QGraphicsView

[veiovis]

Hello,

I want to display hierarchical statecharts with QGraphicsViews.
So every State can contain substates which in turn can i have also substates and so on.
Each state displays its substates in a QGraphicsView, so there are QGraphicsViews in QGraphicsView in QGraphicsView...
Each State inherits from QGraphicsItem and contains a QGraphicsProxyWidget which contains a Widget with a QGraphicsView.

I tested it with a top level state, that contains two substates.
Now comes the strange part:
The first inserted substate is displayed perfectly fine, but the second substate seems to be confused of who its parent is:
The visibility of the 2nd substate depends on the position of the parent state and it can be dragged partly out of its QGraphicsView.
The substates are added with the exact same piece of code.
I made a short video to demonstrate the behavior:
https://www.youtube.com/watch?v=obWVBnKueJc
I am using qt 4.8.

Is it a general problem to have a QGraphicsView inside a QGraphicsView?
Does anybody have a clue why this happens for the second, third etc widget?

Thanks in advance
veio