Thank you for posting.
Unfortunately, the setup for this interface is more complicated than it seems.
The g_HiliteLibrary is a global container field with three repititions - one for each of the three sort icons. The icons displayed on the Record List layout are calculation fields that change depending on the contents of the g_SortBy field.
The g_SortBy field is set whenever you click a column header on the layout. There is actually a hidden rectangle/button object overlaying each header that runs a specific Sort script when you click it. This script sorts the records, sets the g_SortBy field, and consequently changes the result of the calculation field displaying the icon.
Try looking at definitions of the various "Hilite" fields like "HiliteDate" and the sort scripts like "SortDate"; these should give you a better idea of how this interface feature is implemented. If you have any more specific questions, please feel free to post them.
thank you very much!