That does look like a bracket-lib issue. I’ve opened an issue there ( https://github.com/thebracket/bracket-lib/issues/184 ), and I’ll see what I can do. I don’t have a current-gen Pi to test on, hopefully I can figure it out. If I had to guess, it’s a resolution/smoothing issue (you sometimes get rounding errors with GL coordinates, it normalizes everything from 0.0 to 1.0 internally).
Thanks!