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

[Marius Hanl]

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

One thing I noticed in the example in the ticket now: When I click the button below the `TableView`, the `focusWithin` is still 1.
![image](https://github.com/openjdk/jfx/assets/66004280/4faf5585-7b35-4944-a014-d2c0046a7ada)

It seems like the `focusWithin` count is always 2 when the `TableView` is selected. When clicking the button, it will go down to 1, but not 0.

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PR Comment: https://git.openjdk.org/jfx/pull/1210#issuecomment-1683791829