This is for the UX and UI nerds out there: the Aqua Screenshot Library. It’s a collection of various windows, dialogs, screens, and other UI elements in Apple’s Aqua interface in each major version since the Mac OS X public beta. I’ll be curious to see how they handle cataloging Mojave, since there’s light and dark modes for everything. It’s really interesting to see how the interface has continued to evolve (and which aspects remain largely unchanged). You can really see where and how this: 
Became this: 