see DevExpress.Xpf.Grid.EditGridCellData type
http://screencast.com/t/9mQ6LI16
Decompiler - Incorrect visibility is generated for an overridden method
Answers approved by DevExpress Support
We have fixed the issue described in this ticket and will include the fix in our next maintenance update. To apply this solution before the official update, request a hotfix by clicking the corresponding link for product versions you require.
Note: Hotfixes may be unavailable for beta versions and updates that are about to be released.