Registers each of the stock items in items.
If an item already exists with the same stock ID as one of the items, the old item gets replaced. The stock items are
copied, so GTK+ does not hold any pointer into items and items can be freed. Use
add_static if items is persistent and GTK+ need not copy the array.
| items |
a StockItem or array of items |
| n_items |
number of StockItem in |