Helped fix a bug this morning in our code that was last modified on May 1, 2003.
20 years, 10 months, and 27 days ago.
Our code (which we were able to clean up references to and delete, fortunately) was an Obj-C category on NSTableView that now causes a bug in SwiftUI List on recent macOS because SwiftUI uses AppKit for that underneath.
It's simultaneously amazing how long-lived things can be and also what an unstable house of cards all of modern computing is.