Thank you for your feedback.
Yes, this is a known issue. Fortunately, it has been fixed with the Q3 2013 RadControls for ASP.NET AJAX release. You can track this and other changes in our Release History
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to the blog feed