The function set_item_opts sets all the given items option bits (menu option bits may be logically-ORed together).
The function item_opts_on turns on the given option bits, and leaves others alone.
The function item_opts_off turns off the given option bits, and leaves others alone.
The function item_opts returns the items current option bits.
There is only one defined option bit mask, O_SELECTABLE. When this is on, the item may be selected during menu processing. This option defaults to on.
Except for item_opts, each routine returns one of the following: