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,
the Telerik team
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