Occurs before a DataGrid column moves to a new position in the display order.
Assembly: System.Windows.Controls.Data (in System.Windows.Controls.Data.dll)
You can handle this event to customize the visual display of a column header drag-and-drop operation, or to replace the default drag-and-drop behavior completely. To customize the appearance of the dragged column header and the drop location indicator, set the DragIndicator and DropLocationIndicator properties. To replace the default behavior completely, set the Cancel property to true and then provide your own drag-and-drop implementation.
Users can change the column order by dragging column headers only if the CanUserReorderColumns property is true.