https://learn.microsoft.com/en-us/dotnet/api/system.windows.data.bindingoperations.collectionviewregistering?view=netframework-4.8.1&viewFallbackFrom=windowsdesktop-10.0
BindingOperations.CollectionViewRegistering Event (System.Windows.Data) | Microsoft Learn
Occurs when the data-binding system notices a collection view.
event systemwindowsdatamicrosoftlearn