Hi Stephane,
Thank you for your interested in Syncfusion product.
Also sorry for the delayed response. I afraid I was unable to reproduce the issue in GridGroupingControl, when the column order has been changed. We have tested the issue with simple sample,their was no misbehavior occurred in GridGroupingControl. Are you using any other settings with the grid used in your application? Please provide more details on the complete settings like properties, events handled etc.,
Also I have attached the sample in below link.
http://files.syncfusion.com/support/samples/Grid.Windows/7.3.0.20/Forums/GGCControl.zipLet me know if you still face this issue, please try to reproduce the step in this sample. It would be helpful for us to locate the issue and work to provide a better solution.
Regards,
Lingaraj S.