Dynamically changing menus

[Richard Tew <RMT38 student canterbury ac nz>]

I am working on an app which basically contains a menu bar and a notebook.
What I would like to do is change one of the menus, lets say theres the
standard:

+ File + Edit + <changing menu>                  + Help +

menu layout.  I want to alter the 'changing menu' to be relevant to the
current page of the notebook.

So basically, what I am asking is, can I swap one of the menus in the menu
bar (and have the accelerator keypresses updated) at will?  I have looked
at the documentation and read the source but afaict cannot see a way to do
this.

Thanks in advance,
Richard Tew.