RFR: 8371128: NullPointerException occurs due to double cleanup of SwingNode [v2]

[Kevin Rushforth]

On Tue, 4 Nov 2025 17:30:43 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

>> seems like being set in the EDT always
>
> BUT, in line 555 we are accessing lwFrame from the FX app thread, in a completely unsafe manner - test followed by use.

Good catch. Other than being another possible source of an NPE, that one seems unrelated, so might be better handled as a follow-up. This one isn't a threading issue whereas the one you pointed out is.

@prsadhuk Can you at least take a look at it and see whether there is any relation to the bug you are fixing? If not, let's file a follow-up bug. The fix is to also check for null on the EDT before calling createUngrabEvent (as is done in disposeLwFrame -- even if you test lwFrame for null in the FX thread (to short-circuit creating the call on the EDT), you still need to check before use once you actually are on the EDT.

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PR Review Comment: https://git.openjdk.org/jfx/pull/1960#discussion_r2491576342