Thank you for your feedback.
As I mentioned in my previous reply Telerik's Prometheus controls are based on ASP.NET Ajax Framework. If you install ASP.NET Ajax Extensions
when creating a new WebSite you will have the option to create Ajax-Enabled WebSite
whose Web.config will contain the needed settings and you will not need to add them manually. You can find attached a screenshot which shows this option. Otherwise, if your application does not use ASP.NET Ajax you should follow the instructions described in this help article
Regarding the other question you have asked the problem with the stripping of the ContentTemplate
when adding a control inside RadDock in design time is a known issue. We have already logged it in our bug tracking system and will be fixed for one of the next updates of the control. The problem is referenced in a note in RadDock "Prometheus" help in the Getting Started help article
If you have other questions, do contact us again.
the Telerik team