how to access table cell by row & col index

[dkuo123]

I created a table with tree_view,
calculate the total. I can add a Total line after processing all the previous lines. But would like to go back and put the total amount in tree node.
so basically, I want to access the widget in previous row_idx, col_idx and write value there. is it possible?

[rokups]

It is not possible to append data to a previously rendered row. You should calculate total ahead of time and render it first.