Adds item to combo box in ActiveX tag list object.
Syntax
CSV_ListBox_AddItem(hList,sItem,sCategory,sItemID)
#hList:
Handle to list object.
#sItem:
Item text to add to list.
#sCategory:
Category of item (list can be filtered by category).
#sItemID:
ID of item (optional, but if used make it unique for each item).
Return Value
0 if successful, otherwise -1.