[Underphil]

Or use the caps lock key and have that reflected on screen.

[gfd]

Is the caps lock LED even implemented in hardware? I feel like I remember them not responding if my computer freezes but I could be wrong.

[eulers_secret]

I can confirm the LED is not controlled by only keyboard firmware.

I very often use num lock and caps lock responsiveness to check if my PC has hard-locked, and I just recently suffered hard locks while testing S3 on Linux on a new PC. So I am very sure at this point :)

[Underphil]

I only really suggested that because any OS can detect the presence of the CAPS LOCK key (see 'CAPS LOCK is on' during Windows login) and it would make a potentially good marker.

[jrockway]

Caps lock doesn't magically skip the matrix scan.

[Underphil]

Nothing on the keyboard does. I'm trying to suggest an alternative that already has visual feedback.