XmListAddItems man page
XmListAddItems — A List function that adds items to the list
#include <Xm/List.h> void XmListAddItems( Widget widget, XmString *items, int item_count, int position);
XmListAddItems adds the specified items to the list at the given position. The first item_count items of the items array are added to the list. When the items are inserted into the list, they are compared with the current XmNselectedItems list. If any of the new items matches an item on the selected list, it appears selected.
Specifies the ID of the List to which an item is added.
Specifies a pointer to the items to be added to the list.
Specifies the number of items in items. This number must be nonnegative.
Specifies the position of the first new item in the list. A value of 1 makes the first new item the first item in the list; a value of 2 makes it the second item; and so on. A value of 0 (zero) makes the first new item follow the last item in the list.
For a complete definition of List and its associated resources, see XmList(3).