Hi Dan,
The minus sign on the
NumPad isn't considered as a valid input in a
MaskedTextInput control, while the dash key is considered as a valid input in a
Mask="aaa". However, you can customize your
MaskedTextInput to add a dash in its value when the
Substract key is hit by handling the
RadMaskedTextInput KedDown event:
Please give this a try and let me know if it works for you.
Kind regards,
Tina Stancheva
the Telerik team