I gather that this change was reverted, but why does the bug report [1] not refect that?
Also, I believe the proposed change is incorrect, above and beyond its build-breaking feature. (1) It installs the appearances NSAppearanceNameVibrantLight and NSAppearanceNameVibrantDark, which are inappropriate. From the AppKit documentation: Don't assign an NSAppearance <https://developer.apple.com/documentation/appkit/nsappearance?language=objc> object with this type directly to one of your views. Instead, assign a light appearance to your view, make sure its allowsVibrancy <https://developer.apple.com/documentation/appkit/nsview/1483793-allowsvibrancy?language=objc> property is set to YES <https://developer.apple.com/documentation/objectivec/yes?language=objc>, and embed the view in a visual effect view. When you do, AppKit updates your view's appearance to this type. (2) In macOS 10.14, setting an explicit appearance will override the system-provided default. There needs to be a way to prevent AWT from setting the appearance attribute. (3) Dynamic changes to the client property apparently will not work, because _STYLE_PROP_BITMASK is not extended with the new style bit. [1] https://bugs.openjdk.java.net/browse/JDK-8181910
