You can sort any column in the Field List Area just by clicking on it. You will instantly see that the content of the field list is sorted according to your choice. A small arrow in the column header indicates the sorting direction. Below you see a field list sorted descending on the column Fieldname. Note the little arrow!
Note that List Fields will try to "hold on to" the current column. When you sort the list, you might need to scroll up or down to get to the top or bottom of the list.