Discontinguous selections for Sum Toolbar

It would be really useful if one could make discontiguous selections of cells (non-adjacent) and see the Sum Toolbar summaries for them. Excel allows this by Control-clicking on other cells after an initial cell selection.

This would be particularly useful on DataNAV matrixes where you seemingly can’t reorder items other than sorting them ascending or descending, and therefore can’t always get the cells you’d like summarized adjacent to each other.