No, this functionality has not been added yet. As I previously mentioned, this would require quite a redesign of RadGridView and we will include such feature only in case of high demand. So far there are just three requests for the past 2 ½ years.
Also, the forum thread you have mentioned concerns Telerik UI for ASP.NET AJAX, while this forum concerns Telerik UI for WInForms. If you are using the ASP.NET AJAX suite, you can ask in the other thread if their grid supports such functionality.
I hope this helps.
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