RFR: 8313956: focusWithin on parents of a newly-added focused node is not updated [v2]

[John Hendrikx]

On Thu, 17 Aug 2023 00:30:45 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

>> This PR fixes an issue with the way `focusWithin` bits are adjusted in the scene graph. Previously, the `focusWithin` counts of all parents of a removed node would be decreased if the removed node has a non-zero `focusWithin` count. This PR adds logic for the opposite scenario: the `focusWithin` count is increased on all parents of a newly-added node that is already focused (or contains other focused nodes).
>
> Michael Strauß has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Removed unnecessary code

I had a look, but have some questions.

modules/javafx.graphics/src/main/java/javafx/scene/Node.java line 8201:

> 8199: 
> 8200:         // Since focus changes are atomic, we only fire change notifications after
> 8201:         // all changes are committed on all old and new parents.

Is it possible a user can interfere with this process by adding a listener to `focusWithinProperty`?  It fires events when it goes from `true` to `false` and vice versa.

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PR Review: https://git.openjdk.org/jfx/pull/1210#pullrequestreview-1584176874
PR Review Comment: https://git.openjdk.org/jfx/pull/1210#discussion_r1298215694