QAbstractScrollArea doesn't work in QGraphicsScene with QWidget inside items

For Android I need some QListWidget working inside QGraphicsScene. This is mandatory needed for easy scale on different Android screens. QListWidget must have QGroupBox (or any other attached QWidget) attached to each list item. I found this structure does not work. No scrolling if list is longer than visible list part. Vertical scrollbar knob moves between upper and lower positions but list doesn't scroll. Here I attached sample project demonstrating this bug. Without QWidget attached to list items this works fine. To get this just replace 0 to 1 in #if statement inside testlist.cpp file. With just text inside item the list scrolls. Probably bug is in QAbstractScrollArea or in QScrollBar classes. It appears also if QTableWidget used instead of QListWidget.

PS: The list with items scrolls. But QWidgets attached to items stay on place. Probably they get wrong parent.