WindowBuilder Pro is an add-on product that Instantiations has been providing already in the 90ies, when VA Smalltalk was still an IBM Product.
You can still buy it from Instantiations (or their resellers) and they've just announced at StS in Vegas that they'll integrate new Windows widgets with both the Composition Editor and WindowBuilder Pro.
More info can be found here: http://www.instantiations.com/products/add-ons/windowbuilderpro.html
So you can consider WindowBuilder Pro an actively supported Third Party Product, only that the third party is actually the same vendor as the vendor of VA Smalltalk. Maybe you could call that a first-party product
I hope that answers your question