The Insert method inserts a new item into the list of the combo box after the specified item.
The arguments are:
The index (starting with 1) of the list item after which the new item is to be added. If this argument is omitted, the list entry is added after the currently selected item.
A text string added to the list.
A one-based index that specifies the position at which the entry has been added, or 0 or a value less than 0 to indicate an error.