I am creating a GUI with C#. I have a textbox, "ProductName", with ProductName.MaxLength set to 55 (this is for eBay). I want the user to be able to know how many characters they have left to work with. In essence I want this: a dynamic piece of text that shows "55 - len(ProductName)". I'm not very good with C# or XAML, so what do you guys recommend? How do I go about accomplishing this?