[gtkmm] mirroring actions in a user interface

[erik_ohrnberger dme net]

I have a user interface that has a number of notebooks.  The first notebook
allows the user to add and remove pages in the notebook as well as drag and
drop other widgets on this first notebook's pages.

Each action for this first notebook, adding a page, dropping a widget, needs
to be reflected in all the other notebooks.  All the notebooks states need
to be consistent on an ongoing basis.

Presently, I've connected two notebooks in this manner by adding code in the
methods that implement the action in the first notebook, but extending this
technique to more notebooks feels like it would be bulky, repetitive, and
error prone.

What is the best way to make sure that each user action applied to the first
notebook gets propagated to all the other notebooks?

Thanks for your time, thoughts, and experience on this question.

Erik.