Each when you click on a new column to sort by, the previous sort is saved as a secondary sort. If you click the new column again to reverse your new sort, the previous sort will not be changed.
For example, to sort first by Creator and then sort each creator by Name, first click on the Name column header. You can sort click a second time if you want to reverse the sort. Next, click on the Creator column.
SmedgeGui shows a dark icon in the primary sort column, and a light icon in the secondary sort column, so you can see which columns you are sorting on, and if the sort is ascending or descending.