If you execute cut (Ctrl+X) command without any selection in the RadMaskedInput control, you receive a square as first symbol.
Use MaskedTextInput in Silverlight and press (Ctrl + Shift + Z). This will produce unexpected symbol.
Allow the NumPad Substract / Plus key as a valid input in a MaskedTextInput. Reason for decline: The item is duplicated. Please refer to the following link http://feedback.telerik.com/Project/143/Feedback/Details/126323-dash-on-number-keypad-doesnt-work-radmaskedtextinput