The CellValidating event is fired when you try to exit the current cell and navigate to another one either when the editor is active or when the cell is not in edit mode. In both cases, the event is expected to be fired. If the cell is in edit mode, the editor's value will not be committed to the cell until the value is validated. Hence, cancelling the CellValidating event will keep the editor active and the user wouldn't be allowed to exit this cell. A sample approach how to validate the Value in the CellValidatingEventArgs is demonstrated here: https://docs.telerik.com/devtools/winforms/controls/gridview/editors/data-validation
On the other hand, the RowValidating event can be used the same way to prevent the user from exiting the current row. However, the editor will be closed in this case and the value will be committed to the underlying data source. Cancelling the RowValidating event wouldn't allow the user to navigate to another cell.
I hope this information helps. If you need any further assistance please don't hesitate to contact me.
Dess | Tech Support Engineer, Sr.
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