[Pharo-project] How to filter out method extensions in Ring?

Hello all, You may help me on this one. I want to filter out method selectors which are extensions of a particular class. For example, in Pharo 1.4 the ArrayedCollection class has these selectors: ArrayedCollection selectors asSortedCollection I would want all of them except #writeOnGZIPByteStream: which is in "Compression" package. I did a try to Ring ArrayedCollection selectors asSortedCollection collect: [ : each | RGMethodDefinition class: ArrayedCollection selector: each ] with MethodReference I did : ... ( each category beginsWith: '*' ) not ... but it seems not supported in Ring? Any hints? Cheers, Hernán