RFR: 8343336: Add persistentScrollBars preference

[Kevin Rushforth]

On Thu, 31 Oct 2024 17:56:07 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

>> This PR adds another accessibility preference that is available on all supported desktop platforms:
>> 
>> 1. **Windows**: Settings -> Accessibility -> Visual Effects -> Always show scroll bars
>> 2. **macOS**: System Settings -> Appearance -> Show scroll bars
>> 3. **Ubuntu**: Settings -> Accessibility -> Seeing -> Always show scroll bars
>> 
>> When the OS setting is changed, all platforms report updates that can be observed in JavaFX.
>> The manual test application `test/manual/events/PlatformPreferencesChangedTest` can be used to test the feature.
>
> This looks like a useful data point.
> 
> I am curious as to what are the criteria for including or excluding a particular preference?  What is our long term goal - should we support all the preferences available on a particular platform, or the intersection, or what?  May be it's something to discuss first on the mailing list.

Reviewers: @andy-goryachev-oracle @lukostyra 

(I'll look over the public API and the CSR)

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PR Comment: https://git.openjdk.org/jfx/pull/1618#issuecomment-2451898422