Spark DataGrid.draggableColumns

I see there's a property in Spark DataGrid named "draggableColumns". I
expect that when it's set to true that I can change the column ordering.
But it did not work for me and when I looked at the DataGrid code, it looked
like setting draggableColumns to true only dispatches a
"draggableColumnsChanged" event. The search through the sdk for that event
do not yield anything. Was wondering if this implementation complete or in
progress.