You should be able to spellcheck that control if there is a way to get a hold of the client ID of its editing area
. It is most likely an editable IFRAME or <textarea> element. RadSpell should be able to spellcheck it, and the normal operation of the editor will not be interrupted. Remember to set the IsClientID property to true, so that RadSpell knows it is checking a client-side control.
the Telerik team