Problem:If I used master page and put there RadSkinManager how can I used designer in page inherit from the master ? Solution:I can only use the designer in the page where the control is situated. Suugestion:Make proxy for RadSkinManager like RadAjaxManagerProxy
The requested feature will be part of the Web Live Preview integration with the Telerik AJAX control in the browser. You'll be able to select and configure the features directly from the browser - check out this blog post for more information - First Look & Overview of Web Live Preview by Telerik UI for ASP.NET AJAX.