I've been working on an attempt at a modern OpenStep/Cocoa inspired GUI called Merenda [1], but built with modern GPU based stack. The original theme was an Aqua clone but without using any images for the buttons! I used the NextSTEP OpenStep specification as part of the original specs. The workspace ideas were fascinating.
The GUI library aspect is progressing well, but getting a desktop environment going is challenging even with AI. Still I want to capture things like the document workspaces and such. Lately Ive been tempted with making a postscript like display server based on GPU accelerated vector primitives.