GtkHandleBox - detaching menubar by other ways than dragging with the mouse?

["roland" <for_spam gmx de>]

Hello,
i have an application which seems to use GTK.
The menue of the app can be detached and I found this could be the GTKHandleBox widget.

I want to run the application in a "restricted" manner and want to automatically (non interactively) 
detach/undock/remove the menu
bar from the application (moving it out of the user`s sight or even hide/disable it completely, if possible)

Can this be done in any way by NOT using the Mouse - e.g. by a commandline param referencing that widget or 
sending signals to the
program ?

Sorry if this sound`s stupid - but i`m no (gui-)programmer and I`m just looking for a solution.

greetings
Roland

PS:
please reply via mail, too - i`m not subscribed to this list.