[Zope] zope and python global variables?

I notice that zope doesn't like the idea of the file containing functions for use as external modules containing global variable assignments. For that matter, zope doesn't seem to be able to deal with python classes either. I have an application which in its pygtk version consists of a number of global assignments, a number of function definitions, and finally a gtk.main() line. I wish to create a zope version of the same application and one requirement for that is that the application retain its state (global variables) somehow or other. What is the preferred way of doing that in zope?