The notebookbar is not a child window, so trying to graft it on the
SfxChildWindow infrastructure is more pain than gain, unfortunately...

Instead, it's enough to create the appropriate functions for ExecMethod and
StateMethod, and call them from Writer / Calc / etc. with the appropriate .ui
file; that's easier & works equally well.

Change-Id: I08d98d4f481bd02e90ba11df0bd1c1149697a7fa