How to add column total in the bottom of matrix (in a Box).

Hi,

I have a matrix developped with visual studio SDK and I look for the object used to add the "block" containing all columns totals.

In other words, if you look in Inventory, Item Master Data, Inventory Data, and you take a look at the bottom of the matrix, you will see the kind of "Total box" that I need... How to create it in SDK ?

Thanks,

Kevin.