ASPxGridView - How to implement custom date validation in Batch Edit mode

This example illustrates how to implement custom date validation in Batch Edit mode: 
1) The ASPxClientGridView.BatchEditRowValidating event is used to check values on the client.
2) The ASPxGridView.RowValidating event is used to check values on the server.
3) The GridViewBatchEditSettings.AllowValidationOnEndEdit property allows switching validation modes on the client side.  

If the variation between the HireDate and BirthDate columns is less than 18, inputted data is invalid and data update is not allowed.