The RadGrid in News Module - NewsItemsList view is client side bound which does not allow you to call UserManager class. There are two options.
1. Hide edit and delete buttons for items that do not belong to a certain role.
| if (Telerik.Security.UserManager.IsCurrentUserInRole("userGroup"))
| ClientTemplate cTemplae = FindControlRecursive(GridTemplates, "test") as ClientTemplate;
| cTemplae.Visible = false;
Here you need to use recursion to find ClientTemplate control. You should set ID of each ClientTemplate control.
2. Create a custom view and bind it manually on the server. You can use ObjectDataSource. Then in your view you will be able to loop through all items and filter by category.
The current implementation allows you to filter the items - for instance by Category using filterExpressionsAsSQL parameter of DataBindGrid function, but you cannot access the currently logged user.
the Telerik team