At present MenuBar is not a child of RootPane and ContentPane is treated as the only child of RootPane.
In Swing, menuBar and contentPane are children of layeredPane which is a child of rootPane.
ULC does not have layeredPane so ContePane and MenuBar sould be children of RootPane.
Improvement
Closed
Major
ContentPane and MenuBar should be treated as child components in ULCRootPane's containment hierarchy.