RFR: 8349255: TitledPane: exception initializing in a background thread

[Kevin Rushforth]

On Wed, 12 Feb 2025 19:07:19 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

> ## Root Cause
> 
> Animation was started in the background thread, causing concurrent access.
> 
> ## Solution
> 
> Disable animation if not the fx app thread.

The fix looks good. I'll test it later. I left one comment about the change in Parent that I think should be reverted (it's a minor cleanup in a file that you otherwise aren't touching).

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PR Review: https://git.openjdk.org/jfx/pull/1707#pullrequestreview-2615916401