RFR: 8369836: Update HeaderBar API [v2]

[Michael Strauß]

On Tue, 23 Dec 2025 23:34:59 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> Thanks. I saw that, but hadn't had time to respond. I'll do that in the next day or two.
>
> As you no doubt saw from my reply, I didn't get to the discussion. Since this is a preview feature, we can leave the resolution of this until later if you want. I like the idea you have in that thread of providing API to return the declaring class rather than relying on convention. So I think it's OK to leave this how you have it.

In anticipation of `Property`-level support for attached properties, I've decided not to encode the declaring class into the property name at this point.

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PR Review Comment: https://git.openjdk.org/jfx/pull/1936#discussion_r2644822433