Hello, Alberto,
The initially suggested solution in the referred forum thread is to set the
ShowColumnHeaders property to
false. Indeed, this achieves the opposite result. However, if you look at the solution using the
ViewCellFormatting event you will notice that the columns' headers are actually hidden and the group headers remain displayed. There is also a sample project attached to the reply demonstrating the achieved result. It looks similar to the one you need to achieve according to the provided screenshots. Feel free to follow a similar approach.
If you are still experiencing any further difficulties, you can submit a support ticket providing a sample project which demonstrates the undesired behavior. Thus, our support staff will gladly assist you.
I hope this information helps.
Regards,
Dess
Progress Telerik