Accessing fxruby widget from another class

what I am wanting to find out is what is the preferred why of
manipulation a fx widget from another class?

My situation is this.

I have a fxruby class that displays and manages the GUI widgets.

One of these is a progress bar and the program passes control to another
ruby class (has NO fxruby code in it) for the processing of data.

what i’d like is to have this secondary class update the progress bar
that becomes visible before the calling of the other class.

I know I could achieve this by making a global variable ‘$’ but was
wondering if someone could show me a better way.

cheers,

dave.