RFR: 8340852: ScrollPane should not consume navigation keys when it doesn't have direct focus [v2]

[Andy Goryachev]

On Fri, 4 Oct 2024 11:57:56 GMT, John Hendrikx <jhendrikx at openjdk.org> wrote:

>> This change modifies `ScrollPaneBehavior` to only consume keys that are targetted at it.  As `KeyEvent`s are in almost all cases only intended for the targetted node (as visually that's where the user expects the keyboard input to go, as per normal UI rules) consuming key events that bubble up is simply incorrect.  When the `ScrollPane` is focused directly (it has the focused border) then it is fine for it to respond to all kinds of keys.
>> 
>> In FX controls normally there is no need to check if a `Control` is focused (although they probably should **all** do this) as they do not have children that could have received the Key Events involved, and Key Events are always sent to the focused Node.  When `ScrollPane` was developed this was not taken into account, leading to it consuming keys not intended for it.
>> 
>> This fixes several unexpected problems for custom control builders.  A custom control normally benefits from standard navigation out of the box (TAB/shift+TAB) and directional keys.  However, this breaks down as soon as this custom control is positioned within a `ScrollPane`, which is very surprising behavior and not at all expected.  This makes it harder than needed for custom control developers to get the standard navigation for the directional keys, as they would have to specifically capture those keys before they reach the `ScrollPane` and trigger the correct navigation action themselves (for which as of this writing there is no public API).
>> 
>> The same goes for all the other keys captured by `ScrollPane` when it does not have focus, although not as critical as the UP/DOWN/LEFT/RIGHT keys.
>
> John Hendrikx has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Deduplicate lambda

Thank you John for explanations, patience, and the fix!

I don't think this change needs a CSR, but should be definitely mentioned in the release notes.

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

Marked as reviewed by angorya (Reviewer).

PR Review: https://git.openjdk.org/jfx/pull/1582#pullrequestreview-2348269554
PR Comment: https://git.openjdk.org/jfx/pull/1582#issuecomment-2393891011