Yeah i've seen Cuis at the past, it is certainly a leaner Smalltalk compared to Pharo (though TBH i am not a fan of Squeak's UI). If nothing else it can serve as inspiration.
Also now that i think about it, Cuis might be a good Smalltalk environment for starting out or learning about the language in general since i always get the feeling that the more feature packed dialects like Pharo are a bit intimidating.
Juan has done some really impressive work on Morphic3, which uses a vector graphics engine of his own design. He's also pared down Cuis' version of Morphic to its most basic elements, so one could change the appearance of the UI to whatever, theoretically
Also now that i think about it, Cuis might be a good Smalltalk environment for starting out or learning about the language in general since i always get the feeling that the more feature packed dialects like Pharo are a bit intimidating.