Hey! I wanted to let you know that I've been updating my blog on Mars with the latest news, I've just posted some videos showing how different kinds of layouts and widgets are working together on both Cocoa and GTK.
The blog: http://marsonpharo.wordpress.com/. For the ones that are interested in some implementation challenges that I had while building layouts that could work for both Cocoa and GTK, I recommend reading this post: http://marsonpharo.wordpress.com/2013/09/13/the-challenges-behind-building-mars-cross-platform-layouts-on-top-of-cocoa-and-gtk/ Cheers! Carla.