* Can open QtCurve config dialog without crashing
* The MDI's window becomes attached to the actual window it is contained within but it's still better than a crash
Ideally we'd listen for the destruction of the `QWindow` and `unregisterMenuBar` which should avoid the wrong menu showing but this requires more elaborate reengineering. Also, this MDI stuff is quite funky, so I would say this a Qt bug since `QDBusMenuBar` came from Qt mostly unaltered