I have a WPF application with MVVM and need to show a label over a textbox that indicates the remaining number of characters allowed to be in the textbox. I can't seem to wrap my head around the best way to do this.

The user is able to type up to 183 characters in the text box. I would like to show a label above it that indicates (Max Characters: 183). But as they type, I want to show (Remaining Characters: 182). Once they reach 0 it should be 0 but then show in red.

The text box is bound to a property in the View Model which I could get a count on easy enough, however how would I raise the event indicating the text property has changed? WPF does not access the property setters directly.

Timothy