WPF binding fails with custom add and remove accessors for INotifyPropertyChanged.PropertyChanged?

That's just a guess, but I think it might be because the sender parameter passed to the event handler is an instance of HandlesPropertyChangeEvents when the binding expects an instance of MainWindow .

My working solution is almost exactly the same as the "desired implementation" in my question, with the addition of the Sender property.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.