RFR: 8300013: Node.focusWithin doesn't account for nested focused nodes

[Michael Strauß]

On Thu, 12 Jan 2023 03:08:30 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

> When a scene graph contains multiple nested focused nodes (this can happen with `TableView` and other controls), the `focusWithin` bits that are cleared when a focused node is de-focused must only be cleared when there is no other nested node in the scene graph that would also cause `focusWithin` to be set.
> 
> For example, consider a scene graph of nested nodes:
> A -> B -> C -> D
> 
> When B and D are both focused, the scene graph looks like this:
> A(`focusWithin`)
> -> B(`focused`, `focusWithin`)
> -> C(`focusWithin`)
> -> D(`focused`, `focusWithin`)
> 
> When B is de-focused, the `focusWithin` flags must still be preserved because D remains focused.
> 
> This PR fixes the issue by counting the number of times `focusWithin` has been "set", and only clears it when it has been "un-set" an equal number of times.

I think this should go into JavaFX 20.

-------------

PR: https://git.openjdk.org/jfx/pull/993