NumericUpDown ctrl is not detecting validation errors/exceptions

Question

Can anyone confirm or deny that Silverlight's NumericUpDown supports the NotifyOnValidationError and/or ValidatesOnExceptions?

Answer 1

It does and it doesn't.

It does because it derives from Control which is where the binding validation mechanism meets the UI code. It has usual visual states of Valid, InvalidFocused and InvalidUnfocused and with a binding set to notify validation errors the controls visual state will be set to one of this appropriate states.

It doesn't in that the default control template included in the toolkit code does not actually have any UI to represent or display the validation.

Therefore in order to support NotifyOnValidationError you will need to copy and edit the default template and add some UI for the validation. You can get some idea of the needed validation UI by looking at the template for a TextBox.