RFR: 8345348: CSS media feature queries [v21]

[Andy Goryachev]

On Tue, 6 May 2025 20:23:10 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

>> That's why I am against this background thread nonsense.  Create - yes (even though I am against this).  Access and modify properties, especially those that interact with other parts of the FX - no.
>> 
>> I think we should enforce the FX application thread access.
>
> This would be a significant change, as currently `Scene` is explicitly allowed to be created _and modified_ on a background thread. This was probably always a very bad idea (because it makes the implementation so much more difficult), but how do you think we should change that?

how about: 

- the implementation must not fire any events before the Scene is shown
- the preferences getters should disallow calls from a background thread

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PR Review Comment: https://git.openjdk.org/jfx/pull/1655#discussion_r2076229687