When High Sierra came out we got reports of a regression in Sourcetree’s dark theme. Building that was an adventure of its own so I was a bit concerned about what might have broken.
After sitting down with the Xcode debugger I stepped through and verified all theming code and appearances were still correct and being hit. Next up was checking the visual hierarchy for what view was problematic.
Poking around further I found that particular view wasn’t set to -wantsLayer. Previously it picked this up implicitly.
One line later and we’re back in business.