I've employed a grid class with the common method of sorting the grid
by clicking the header. The index is assumed to be the field name.

Now I need to go further for our users. Above the grid I would like to
have maybe three or four comboboxes that users can set their own combination of a sort order. So instead of my current method that only allows sorting on "part number" OR "part description" OR "Location" we can sort on "part number" then "part description" then "Location or "part description" then "location" or "Location" then "part description" etc... I cannot see the creation of all the index combinations to cover the possible sorting combinations. Not sure how to proceed. Any tips?