Make `SelectionModel.SelectedItems` and `SelectionModel.SelectedIndexes` implement `INotifyCollectionChanged` so that they can be bound to.
As well as implementing `INotifyCollectionChanged` on the collections, we also had to implement `IList` (see #8764) so refactored this out into a base class.
For the sake of simplicity, these collections only raise `Reset` for any change: this is may need to be changed later but I'd rather follow the KISS principle for the moment until something more complex is proven necessary.
Fixes#15497
* Added failing tests for #12733.
* Clear SkipLostSelection on batch update start.
If `Source` is changed during a collection update, then the `Clear()` operation will not be committed immediately due to `_isSourceCollectionChanging` being set. In this case, `update.Operation` will still have `SkipLostSelection == true`, meaning that `LostSelection` will not be raised, causing #12733. Clear the flag manually each time `BeginBatchUpdate` is called to avoid this.
Fixes#12733
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Co-authored-by: Max Katz <maxkatz6@outlook.com>
- Remove `SelectedItemsSync` and store `SelectedItems` in a new `InternalSelectionModel`
- Store transient `SelectingItemsControl` state in an `UpdateState` object
Fixes#4272
`IEnumerable<T>` is not covariant for value types, so we need to use the non-generic `IEnumerable` everywhere under the hood to ensure we can work with both value and reference types.
Julien Lebosquain
Nikita Tsukanov
Steven Kirk
Steven Kirk
Andrey Kunchev