RFR: 8334593: Adding, removing and then adding a JFXPanel again leads to NullPointerException [v3]

[Prasanta Sadhukhan]

On Mon, 1 Jul 2024 20:43:44 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

> Kevin is right, this fix does not solve the issue mentioned in the ticket. Once the fxPanel is added back, its content is not visible. Does not matter whether removing/adding happens at startup or the button event handler.
> 
> (attaching a slightly modified test case to the ticket, notice lines 30 and 44.
> 
> Also, I think swing requires validate() and repaint() called after modifying the component's children.

OK..I guess I probably misunderstood the expectation...it says

EXPECTED -
The JFXPanel is visible to the user of the application and no Exceptions are thrown.
ACTUAL -
The JFXPanel is visible but the following Exception is thrown

which I deciphered as the JFXPanel window being visible and I guess in original testcase execution, the "TestButton" was still visible, only NPE was thrown..

ANyway, I guess it was mentioned that "We should file a follow-on Enhancement to consider doing this" and regarding synchro mentioned at line58, I guess we already have `QuantumToolkit.runWithRenderLock` in the problematic code

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PR Comment: https://git.openjdk.org/jfx/pull/1493#issuecomment-2201826620