keyok - enable or disable a keycode
int keyok(int keycode, bool enable);
This is an extension to the curses library. It permits an application to disable
specific keycodes, rather than use the keypad function to disable all
keycodes. Keys that have been disabled can be re-enabled.
The keycode must be greater than zero, else ERR is returned. If it does not
correspond to a defined key, then ERR is returned. If the enable
parameter is true, then the key must have been disabled, and vice versa.
Otherwise, the function returns OK.
These routines are specific to ncurses. They were not supported on Version 7,
BSD or System V implementations. It is recommended that any code depending on
them be conditioned using NCURSES_VERSION.