RFR: 8343398: Add reducedData preference [v10]

[Kevin Rushforth]

On Fri, 20 Dec 2024 15:01:00 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

> Correction: the listeners no longer get notified after the FX toolkit is stopped, perhaps due to the fix for[JDK-8335630](https://bugs.openjdk.org/browse/JDK-8335630). Needs more investigation.

This is not related to JDK-8335630. The notification does get delivered, but ends up going through the "else" block in the following code in `PlatformImpl::updatePreferences`:


        if (isFxApplicationThread()) {
            checkHighContrastThemeChanged(preferences);
            platformPreferences.update(preferences);
        } else {
            // Make a defensive copy in case the caller of this method decides to re-use or
            // modify its preferences map after the method returns. Don't use Map.copyOf
            // because the preferences map may contain null values.
            Map<String, Object> preferencesCopy = new HashMap<>(preferences);
            runLater(() -> updatePreferences(preferencesCopy));
        }


This happens because `isFxApplicationThread()` returns false after the toolkit is stopped (see `Application::finishTerminating`). The `runLater` at the end of the else block never runs and the runnable is discarded, so the else block ends up being a no-op.

So I think my recommendation of "maybe file a P4 bug to look at later" is the most that is needed here.

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PR Comment: https://git.openjdk.org/jfx/pull/1656#issuecomment-2557378425