You can also log such a feature request about the RadHtmlChart in our feedback portal - http://feedback.telerik.com/Project/108. If you log it and provide a link to it here, we will be glad to award you with Telerik points for the efforts.
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