Demo app does not work on macOS Big Sur 11.4

[nsmoker]

When running OsThemeDetectorDemo on Big Sur 11.4, changing the OS theme does not result in any printouts like it should. The isDark function can correctly identify whether or not the system is in dark mode, but the listener is not called when the OS theme is changed.

The value of OsThemeDetector.getDetector().getClass().getName() is com.jthemedetecor.MacOSThemeDetector, so it would appear that this is not an issue of the detector implementation being determined incorrectly.

The graphical demo app does work.

[Dansoftowner]

Thanks for reporting the issue!
Does it work if you initialize the OsThemeDetector instance on a background thread?
Like this:

ExecutorService executor = Executors.newSingleThreadExecutor();
final OsThemeDetector detector = executor.submit(OsThemeDetector::getDetector).get();
...

[nsmoker]

Hey, sorry for the delay. Unfortunately, using a background thread doesn't appear to change anything. Could be related to this SO thread. Based on some tests I did with my own wrapper around the Obj-C runtimes and Foundation, it seems like Mac will only send you InterfaceStyleChanged notifications if you have already have an NSApp running somewhere, which makes listening for those notifications useless and breaks the theme detection for CLI tools.