We decided to update the RadControls to the latest Q1 2012
with the next Service Pack. You are right that currently the version with Sitefinity 5.0
is Q3 2011
If you have a license for the ASP.NET AJAX Suite you can download and replace the Telerik.Web.UI.dll, Telerik.Web.UI.Skins.dll and Telerik.Web.UI.xml from the bin folder of the Sitefinity Web Application with the latest dll-s from the ASP.NET AJAX Suite, however Sitefinity is tested for stability with a version of the RadControls that doesn`t cause problems so it will remain the officially supported version.
Please let me know if you need further assistance.
the Telerik team
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