Inserts an item in control and returns index of new item or -1 if unsuccessful. TIP: Do not assume that the item you add with InsertItem() is given the index you requested; InsertItem() returns the actual index of the item added. If you insert past the upper bound of the control, your item is added to the end.

public SalNumber InsertItem(
	SalNumber nItem,
	SalString sText,
	SalNumber nImage
)