Automatic dark mode detection (JDK-8235460) - POC

[Pavel Rappo]

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On Thu, Oct 30, 2025 at 5:23 PM axh <axh at dua3.com> wrote:
>
> Hi,
>
> I hope this is the right place to ask - I would comment in the bug tracker if getting a login there weren’t harder than entering Fort Knox. If this should be posted to another list, please let meknow.
>
> I have written a POC for dark mode detection that works on Windows, MacOS, and Linux. It is 100% Java, calling native code through FFM, so Java 25 is required. It can detect the current system setting, and also tracks system changes.
>
> I have released the POC under the GPL V2 with classpath exception to make it compatible with OpenJDK/JavaFX licensing.
>
> Needs Java 25 and JavaFX correctly set up on your system (JavaFX is only needed because of the JavaFX sample application).  No external libraries are needed (in the POC, I changed logging to use the system logger).
>
> Legal thought
> - I have used web search to find out how to detect and listen to system changes.
> - I have also used AI to implement the necessary calls using FFM as I don’t yet have much experience with it. As everything is quite straight forward (follows established well documented practice for the platform) and the AI mainly helped me to put it into a FFM compatible form, I think there is no risk to inadvertently touch any third party copyright issues. I just want to mention that in case it is seen as a problem
>
> The POC is available on GitHub: https://github.com/xzel23/darkmodedetector
>
> Please let me know if this would be an acceptable contribution, and if so, how to proceed.
>
> Axel
>
> PS: Sorry to the mods, I accidentally used the wrong sender previously.
>