Could you please take a step back and try to explain what is your final goal and what exactly you have done so far? Why you need custom datasource? Why you need to override the CellForItem() method? Also it would be really helpful if you provide additional details about what your current issue is. What you need to achieve? Hopefully, this information will give us a better overview on our work and will be able to understand exactly what you have in mind and respectively assist you on your way.
Pavel R. Pavlov
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items