Ofcourse we can look for an empty slot, but that won't do much good as soon as we've seen more than 8 satellites, in which case we would go back to the broken behaviour.


Yeah, my instincts flared when I saw the fix, but I didn't chase it
wrt to the shading - what I'm saying is that I always see VFDSHADE_MEDIUM, and never _BRIGHT, so doesn't appear to be working how you hoped. But is probably also due to timestamp never being initialised - the comparison is based on gps->time and gps->sat[i].time, and we've realised that the latter is always wrong.

But, I'd prefer knowing which sats are being used in the solution - as you've described, BRIGHT for used, MEDIUM for current but unused, and open for stale.