RFR: 8301312: Create implementation of NSAccessibilityButton protocol

[Ambarish Rapte]

On Thu, 6 Apr 2023 20:43:13 GMT, Alexander Zuev <kizune at openjdk.org> wrote:

> Add the common base component for all the new implementing native classes Change native peer creation to use the new base component The new code will instantiate new protocol implementation  for the given role if it exists or an old one if it does not exist
> Added BUTTON role implementing class

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.

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PR Comment: https://git.openjdk.org/jfx/pull/1084#issuecomment-1504791569