RFR: 8349004: DatePicker: NPE in show() when initialized in a background thread

[Kevin Rushforth]

On Wed, 12 Feb 2025 19:45:32 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

> ## Root Cause
> 
> Focus is being requested in show(), even a background thread.
> 
> ## Solution
> 
> Do not request focus if in a background thread.

I took a quick look at PR #1709 which has a similar problem with its show method, and there is a third option we should consider:

3. Change the implementation of all skin show methods to do nothing (bail out early) if not on the FX application thread. If we do this, I would want to see it documented.

In any case, I'd like to pause the reviews of the individual PRs that touch the skin's `show` method until we resolve the larger question of what to do about `*Skin::show`.

One thing that would help inform the discussion:

Why did you call show in the first place in your NodeInitStressTest (for that matter, why directly call _any_ skin methods, since apps generally don't)? Was it just something you did to stress it, or is it reflective of a normal operation that an app might do during initialization of a node on a background thread? I have a feeling it's the former, but maybe I'm missing something.

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PR Comment: https://git.openjdk.org/jfx/pull/1708#issuecomment-2655054885