HEADS-UP: Threading restriction for Animation play, pause, stop now enforced

[Kevin Rushforth]

As a heads-up for app developers who use JavaFX animation (including 
Animation, along with any subclasses, and AnimationTimer), a change went 
into the JavaFX 22+5 build to enforce that the play, pause, and stop 
methods must be called on the JavaFX Application thread. Applications 
should have been doing that all along (else they would have been subject 
to unpredictable errors), but for those who aren't sure, you might want 
to take 22+5 for a spin and see if you have any problems with your 
application. Please report them on the list if you do.

See JDK-8159048 [1] and CSR JDK-8313378 [2] for more information on this 
change.

Thanks.

-- Kevin

[1] https://bugs.openjdk.org/browse/JDK-8159048
[2] https://bugs.openjdk.org/browse/JDK-8313378