Is there is a way to a column as a calculated running total of another column?  Example:

Order#    Weight      Cuml weight

A             5               5

B             10             15

C             6               21

I know this can be done using SQL SUM…OVER(ORDER BY) clause, but would prefer to do with on_data_display callback function.  With SQL clause, if user clicks on Weight column to sort, Cuml column is still based on Order #.