WPF dependency property setter not firing when PropertyChanged is fired, but source value is not changed

Question

I have an int dependency property on my custom Textbox, which holds a backing value. It is bound to an int? property on the DataContext.

If I raise the PropertyChan

Answer 1

The XAML will call SetValue directly, instead of calling your property setter. I can't remember exactly the specifics, but I ran into a similar problem a while ago. You should not put any logic in the setter for Value, instead define a callback for when the Dependency Property changes, and update the value from there.