Thanks for contacting us and for the reported issue. It seems that this issue is more specific since we are not able to reproduce it and you are the first to report this behavior. Could you please share some more details about your environment like whether you are using Remote Desktop Connection or any custom Desktop Settings (color depth etc.).
Also make sure that you have the latest drivers for your video adapter installed on your machine since old driver versions are often cause for similar glitches.
I look forward to receiving the requested details.
Thanks for your time.
the Telerik team