Floating a docked widget that has a custom title bar causes a crash

Create a main window with two docked widgets
Assign a custom title bar to the docked widgets
Attach a slot to the topLevelChanged signal and in this call setTitlebarWidget with 0 or the custom title bar depending upon whether the widget is being floated.
When moving the docked widgets it can result in a crash in QLayoutItem *QDockAreaLayoutInfo::unplug(const QList<int> &path)