Hi Diego,

Thank you for submitting this feature request. We will consider adding such an enhancement based on the customer demand.

Meanwhile we can suggest the following approach for achieving it via a custom implementation involving currently existing built-in features of the Grid:

Use the Grid expansion directive to store the IDs of all expanded items, and some simple custom logic to add a class to the expanded rows conditionally via the rowClass callback, based on the presence of the ID of each item in the ExpandedKeys array, e.g.:

Regards,
Dimiter Topalov
Progress Telerik