docked widgets and custom title bars

Hi
I have an application that has a docked widgets with custom title bars.
When a docked widget is floated I wanted it to take on the native look so I implemented a slot to handle the topLevelChanged signal. In this slot I set the titleBarWidget to 0 if the widget is floating or to my title bar widget if not.
When I run this application it has a tendancy to crash when moving the docked widgets around.

Is this a known problem?
If so is there a work around?

Graham