Indeed there are breaking changes in the embedded RadControls skins in order to unify their css class names (an important step before the first release of the ASP.NET Visual Style Builder tool we plan to announce for Q2 2009) and improve/polish their look and feel. These modification are outlined in the relevant article from the documentation:
Therefore, if you would like to use the old skin with the new versions of the controls, I suggest you use the skin converter we prepared for this purpose. How to use this tool you can see from the following blog post
on our site.
You can use the assembly from the /bin35
folder of the installation for projects built on top of ASP.NET 3.5 and the assembly from the /bin
folder for ASP.NET 2.x or ASP.NET 3.x projects.
the Telerik team