OpenWebstart get stuck on certificate selection screen (multi-threading with event dispatch thread hack)

[merkisoft]

I was able to reproduce this with a self-issued certificate on localhost.

The problem exists when doing a backend call in a SwingUtilities.invokeLater at the same time as a background thread calls a the backend to the server with a broken certificate.

Result: the certificate dialog and the UI are completely frozen.

Now it's super easy to reproduce, see my comment: https://github.com/karakun/OpenWebStart/issues/594#issuecomment-2498960727

I suspect that the locking does not work properly in this case, in the following section: https://github.com/AdoptOpenJDK/IcedTea-Web/blob/d8414248348bc2b08cb5f97926decaa491a0dfa8/core/src/main/java/net/adoptopenjdk/icedteaweb/client/parts/dialogs/security/SecurityDialogs.java#L305

            message.lock = null;    
...

            // background thread
            message.lock = new Semaphore(0);
            ...
            message.lock.acquire();

and most likely both call JNLPRuntime.getSecurityDialogHandler().postMessage(message);

btw this issue was first raised here: https://github.com/karakun/OpenWebStart/issues/594 but the broken code is in this repo (14 year old code ... :-))