Please take a look at this post
. You can map the template of the GontentBlock designer from Sitefinity's configuration ( take a look at attached screenshot) and then set the property of theHtmlField control.
the Telerik team
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 Public Issue Tracking
system and vote to affect the priority of the items