Embedded QDialog in QGraphicsScene lost their window decorations in Qt 4.6

I discovered a problem after upgrading to Qt 4.6.x. My debug dialogs embedded into a graphics view/scene lost their window decorations. After a bit digging, I could find out that the problem was that I set the appropriate window flags of the QDialog, but left the default flags for the QGraphicsProxyWidget. Somehow the thing worked in Qt 4.4.x/4.5.x, did not work in Qt 4.6.x. The solution was to pass the same window flags to the proxy widget as well.