I whipped up a little library to inject into previously-crashing apps, like Mail, awkwardly patching NSDrawer and NSToolbar support back into Platinum 😅 Even getting Project Builder up and running required a bunch of little tweaks.
It’s fun to know that it would be entirely plausible to patch Aqua almost completely out of the early versions of Mac OS X. I had no idea any of this survived, in such a complete form, past the Developer Previews/PB
Bonus screenshot of OmniGraffle running in the OPENSTEP-style interface, on Mac OS X v10.0