If nth is negative writes No Match in the mini
buffer, else highlights the nth character if it is
visible, else writes Match '<the char>' at line <the
line> pos <nth>. This function is used by the
C-mode (§5.28 page ) when you press
},)
and
]
keys to indicate corresponding {,(
and
[
position. Obviously its visibility effect is obtained
when blink is called, not when the current Smac
execution is finished.