Can you please provide more details about your setup. I have attached my example, which shows RadChart in RadWindow and the tooltips appear as expected. Can you please attach a similar example, which shows the issue or modify this one and send it back to us? Thank you.
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