FKEY
action |= FKEY;
case FKEY | SPCLKEY: /* a function key, return string */
case FKEY: /* function key */
case SPCLKEY | FKEY | F(49): /* home key */
case SPCLKEY | FKEY | F(57): /* end key */
case SPCLKEY | FKEY | F(50): /* up arrow key */
case SPCLKEY | FKEY | F(58): /* down arrow key */
case SPCLKEY | FKEY | F(51): /* page up key */
case SPCLKEY | FKEY | F(59): /* page down key */
case FKEY: /* function key, return string */