RFR: 8349373: Support JavaFX preview features

[Andy Goryachev]

On Tue, 4 Feb 2025 18:41:13 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

>> PREVIEW-FEATURES.md line 32:
>> 
>>> 30:    application has not opted into the use of preview features. All preview features have equal status
>>> 31:    in any given JavaFX release and can not be enabled individually.
>>> 32: 
>> 
>> do you want to talk about similarities and differences between this and jdk preview features https://openjdk.org/jeps/12 ?
>
> This definition is, as you point out, largely lifted from JEP 12. Aside from wording changes, here are some key differences:
> 
> * JEP 12 assumes that a feature should be finished within two releases. I think for JavaFX, being just a framework and not a programming language, it is sensible to assume that we can finish features in the next release; that is, a preview feature that is introduced in JavaFX N should be finished in N+1.
> * JEP 12 says that a preview feature should be at least 95% "done". I think we can be a little bit more risk-tolerant here, which is why I lowered this number to 90% "done".
> 
> The general idea is that preview features in JavaFX should be faster and accept a little bit more risk than preview features in the JDK.

The space of people who know what a JDK preview is is larger than that of JFX people.  I think we might want to point to JEP12 and explicitly explain the difference, that's all.

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PR Review Comment: https://git.openjdk.org/jfx/pull/1359#discussion_r1941721364