RFR: 8196065: ListChangeListener getRemoved() returns items that were not removed. [v6]

[Michael Strauß]

On Fri, 28 May 2021 14:31:14 GMT, Jeanette Winzenburg <fastegal at openjdk.org> wrote:

>>> You mean `selectedIndices` not reporting truthfully?
>> 
>> Yes, I meant `selectedIndices`.
>> 
>> I'm not quite sure I understand what you're getting at. Are you suggesting to apply the changes reported by `selectedIndices` to our copy of the items (`itemsRefList`) while iterating the changeset? If so, I think that doesn't work because crucial `selectedIndices` notifications are missing.
>> 
>> For example, `selectedIndices` sometimes doesn't report removed items. By simply iterating over the changeset, `itemsRefList` would soon be out of sync with `selectedIndices`. The only way to correctly sync `itemsRefList` with `selectedIndices` is to discard all items, and collect them again in a bulk operation (like it's done currently).
>> 
>> That alone doesn't make `SelectedItemsReadOnlyObservableList` well-behaved: since its change notifications are generated while iterating over the `selectedIndices` changes, it will also miss some notifications.
>
>> I'm not quite sure I understand what you're getting at. Are you suggesting to apply the changes reported by `selectedIndices` to our copy of the items (`itemsRefList`) while iterating the changeset? If so, I think that doesn't work because crucial `selectedIndices` notifications are missing.
>> 
> 
> exactly, that's what I meant right from the start (and obviously haven't been clear enough ;) And now I understand what you tried to explain to me, probably also right from the start .. thanks for spelling it out!
> 
> hmm .. so we are stuck with a severely misbehaving selectedItems that's trying to do its best to compensate for the misbehaviour in selectedIndices (there are not only missing but also badly incorrect, notifications see f.i. [JDK-8267781](https://bugs.openjdk.java.net/browse/JDK-8267781)). There probably should be some documentation to explain that fact. Maybe open a follow-up issue to make sure the selectedItems are revisited?

Yes, this should be followed up on. [Here](https://bugs.openjdk.java.net/browse/JDK-8267951)'s the issue.

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PR: https://git.openjdk.java.net/jfx/pull/478