Thank you for contacting us.
Unfortunately, this is not possible with the current implementation of the RadWindow control. However, this request is already added in our Public Issue Tracking System (PITS). You can view it here
. You can vote for it, track its status and see when it is going to be implemented.
If you have further questions please let us know.
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? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items