You can submit a feedback request here for the development team to consider adding a mask annotation as they work on the next release of the control. Requests and Bug reports submitted through the portal go directly into the team's backlog.
Lance | Tech Support Engineer, Sr.
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items