Delete triggering ModelPropertyChanged for BusinessListBase but not BusinessBindingListBase in Blazor

[rockfordlhotka]

Discussed in #2951

^{Originally posted by michaelcsikos May 23, 2022}
I have two collections, one inherits from BusinessListBase, and the other from BusinessBindingListBase. Each collection is wrapped in a ViewModel<T>. The PropertyChangedEventHandler from the root edit page is passed down to all the children:

// Root edit page
private async void PropertyChanged(object? sender, PropertyChangedEventArgs e)
{
    await InvokeAsync(() => StateHasChanged());
}

// In each child collection
[Parameter]
public PropertyChangedEventHandler PropertyChanged { get; set; }

protected override void OnInitialized()
{
    VM.ModelPropertyChanged += PropertyChanged;
}

In the collection ViewModel, child items are deleted like this:

 public void Remove(WidgetVM context)
 {
     if (Model == null)
         return;

     Model    .Remove(context.Model);
     WidgetVMs.Remove(context);
 }

For the BusinessListBase deleting a child item triggers PropertyChanged, it bubbles up to the root edit page and the Save button becomes enabled, but it's not bubbling up for the BusinessBindingListBase. Ordinarily I would just use BusinessListBase to solve it, but we have some classes which are used in WinForms as well.

Am I approaching this correctly, i.e. making a VM to wrap each collection, and a VM to wrap each child item, and passing PropertyChangedEventHandler down?