To reproduce this, place the attached program in the same directory as PlatformPreferencesChangedTest.java (which is in tests/manual/events/ in the repo) and run it:

$ java PlatformPreferencesInitAWTFirst

BUG: neither the initial properties nor any changed properties are read.

This bug is specific to macOS. The same test works on Windows.

Workaround 1: Set the system property "apple.awt.application.appearance=system" prior to initializing the AWT toolkit.

Workaround 2: initialize the JavaFX runtime before the AWT toolkit.