>>>>> "c" == craig duncan <duncan / nycap.rr.com> writes: c> class << SampleWindow c> include SampleClass c> end I think this is the same than class SampleWindow extend SampleClass end The difference is that * in the first case, the method #append_features is called * in the second, the method #extend_object is called if you don't redefine these methods you end with the same result. Guy Decoux