RFR: 8294589: MenuBarSkin: memory leak when changing skin [v15]

[John Hendrikx]

On Thu, 1 Dec 2022 19:47:52 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

>>> but instead the whole component or Pane might be removed from the scene and discarded.
>> 
>> If that happens, weak reference won't make a difference there either. Removing an entire branch from the Scene and not referring to it anymore will do correct clean-up even without a call to dispose and without the use of weak references.
>> 
>> The only use case I see is that we still don't trust the Skin lifecycle to be adhered to and "just in case" are using weak references in case somehow dispose is not called. I would much prefer to see an actual reason to use it, and then adding a comment as to why this weak reference is needed so that in 6 months time we're not scratching our heads as to why a weak reference is needed here.
>
> just to be sure, which weak listener are you referring to?

I didn't mean a weak listener, but a weak reference.  This line creates one:

     sceneListenerHelper = new ListenerHelper(MenuBarSkin.this);

I think a plain `new ListenerHelper()` would work correct here.  If you don't think so, I think it may be good to add a comment why the weak reference is needed to make the clean up work correctly.

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PR: https://git.openjdk.org/jfx/pull/906