private void RadGridView_CellLoaded(object sender, Telerik.Windows.Controls.GridView.CellEventArgs e)
{
	if (e.Cell is GridViewHeaderCell)
	{
		Dispatcher.BeginInvoke(new Action(() =>
		{
			DragDropManager.AddDragInitializeHandler(e.Cell, OnHeaderCellDragInitialize, true);
		}));
	}
}

private void RadGridView_CellUnloaded(object sender, Telerik.Windows.Controls.GridView.CellEventArgs e)
{
	if (e.Cell is GridViewHeaderCell)
	{
		Dispatcher.BeginInvoke(new Action(() =>
		{
			DragDropManager.RemoveDragInitializeHandler(e.Cell, OnHeaderCellDragInitialize);
		}));
	}
}

private void OnHeaderCellDragInitialize(object sender, DragInitializeEventArgs e)
{
	var dragSource = e.OriginalSource as GridViewHeaderCell;
	if (dragSource != null)
	{
		var dragVisual = new Border()
		{
			BorderBrush = Brushes.LightGray,
			BorderThickness = new Thickness(1),
			Background = new SolidColorBrush(Colors.Bisque) { Opacity = 0.4 },
			Width = dragSource.ActualWidth,
			Height = dragSource.ActualHeight,
			Child = new TextBlock() 
			{ 
				Text = (string)dragSource.Column.Header,
				Margin = new Thickness(5, 0, 5, 0), 
				VerticalAlignment = VerticalAlignment.Center }
		};
		e.DragVisual = dragVisual;
	}
}