Looking back in ruby-talk for 'Ruby' and 'XUL' shows a discussion from 
November of last year about creating an XML/XUL based scheme for creating 
toolkit-agnostic GUIs.  There was some discussion of this as a project, 
I'm just wondering if anyone starting putting anything together.

I'm currently deveoping a Ruby/FLTK GUI, but there is some talk about 
moving to a Mozilla-based solution and it would be nice if I could just 
code up the GUI in XML/XUL and then either generate the FLTK code or take 
the XUL directly to Mozilla.

I'm wondering how callbacks would work though.  I suspect that you could 
have some classes that define callback methods in a similar manner for all 
supported toolkits.

Anyway, just wondering if anyone has started working on something like 
this.

Phil