RFR: 8301312: Create implementation of NSAccessibilityButton protocol

[Alexander Zuev]

On Wed, 12 Apr 2023 07:22:54 GMT, Ambarish Rapte <arapte at openjdk.org> wrote:

> I noticed two behavioral change, when VoiceOver is running.
> 
> * Focus Rectangle:  A Black (focus) rectangle is drawn around a focused control, or an item that has Accessibility focus. This seems correct and offers more visual information.
> * Control + Option + space key and only space key can perform an action on two different controls at the same time.
>   Steps to observe:
> 
> 1. Launch Ensemble and run Timeline sample from Animation section.
> 2. Notice there are four buttons.
> 3. At launch the button Start gets focus and focus rectangle.
> 4. Press Space or Control+Option+Space button, both would trigger same Start button.
> 5. Press tab once, the focus moves to Pause button.
> 6. Press and hold Control+Option and press right arrow key two times.
> 7. The black focus rectangle moves to Restart button but Pause button retains the focus.
> 8. Pressing space button would trigger Pause button and
> 9. Pressing Control+Option+Space button would trigger Restart button.
>    => I am not sure if this is expected behavior.
>    => Similar behavior is not observed with a simple AWT sample with three buttons added to Frame.

This is expected behaviour. The square block is an accessibility cursor and it can be different from the keyboard focus. Pressing space will trigger action on the button from the FX side and Ctrl+Option+Space will launch an action from the accessibility subsystem. Note that my change does not alter this behaviour, FX acted the same before it.

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PR Comment: https://git.openjdk.org/jfx/pull/1084#issuecomment-1550835722