For the functionality of formatting a range of cells as a table, I suggest submitting a Feature Request. Because the RadSpreadsheet is a Web Forms wrapper for the Kendo widget, the Feature request should be submitted in the Kendo UI feedback portal at Progress® Kendo UI® for jQuery Feedback Portal. Once the Feature is implemented in the Kendo widget, it will also be available in the Web Forms RadSpreadsheet component.
Regards,
Attila Antal
Progress Telerik
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