RFR: 8349105: Pagination: exception initializing in a background thread

[Kevin Rushforth]

On Thu, 6 Feb 2025 20:43:54 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

> ## Root Cause
> Animation gets started in a background thread, which causes the animation handler to run in the FX application thread, thus creating simultaneous access to the control's fields (list of children in this case).
> 
> ## Solution
> Postpone the animation unless running in the FX application thread.  There is no functional difference if the component is created/used in the FX application thread.

The test runs out of heap space for me on Windows with or without your fix using the default heap size. This may point to a leak, although bumping up the memory causes it to pass with your fix.

The fix looks good, although the test doesn't catch the bug most of the time (even when bumping up the heap).

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PR Review: https://git.openjdk.org/jfx/pull/1698#pullrequestreview-2600480255