Hello Amir,
Thanks you for your interest in our control suite.
This is a very nice suggestion, we will log it for future implementation as a separate control.
For the moment you can use the RadComboBox and to populate it with the data you need.
You can use numbers and letters to populate the RadComboBox ItemsSource property.
Check the examples with RadComboBox here:
http://demos.telerik.com/silverlight/#ComboBox/Events
Please let us know if you need any help implementing this.
Kind regards,
Valentin.Stoychev
the Telerik team
Check out
Telerik Trainer, the state of the art learning tool for Telerik products.