Hello NS,
First of all, I'd like to thank you for your feedback. The current version of RadControls has limited theming support (the only exception is RadGridView). We plan to add full theming support to all of our controls with the forthcoming Beta 2 release which is due mid-July.
I appologize for any inconveniences you may have experienced.
Greetings,
Hristo
the Telerik team