When apply pre-defined css class (from class dropdown) to <p> in editor it wraps the paragraph text with <span> and applies class to <span>
E.g. on your demo page Telerik Web UI Editor Overview Demo | Telerik UI for ASP.NET AJAX after apply .red-text to the first paragraph it resulted in
<p><span class="redText"><strong>Barcelona </strong>is an excellent place to discover world-class arts and culture. The sights in Barcelona are second to none. Don’t miss the architectural wonder, <a href="http://demos.telerik.com/aspnet-ajax/imagegallery/DestinationDetails?Id=1"><em>Casa Mila</em></a> - otherwise known as La Pedrera. You’ll want to see another one of Antoni Gaudi’s architectural masterpieces, <a href="http://demos.telerik.com/aspnet-ajax/imagegallery/DestinationDetails?Id=1"><em>Casa Batllo</em></a>, which is located at the center of Barcelona.</span> </p>
How to apply that class to <p> using toolbar and not switching to html mode?