You may predefine the template of GridViewGroupPanelCell and remove the animation, which manipulates the Opacity of the part named PART_CloseButton. Mark this style as an implict one and it will be applied each time when you drag and drop column header in RadGridView's GridViewGroupPanel.
I am attaching you sample application which demonstrates how this can be achieved.
If you need any further assistance do not hesitate to contact us!
All the best,
Vanya Pavlova
the Telerik team
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