My question was just "caught in a spam net" - why? Anyway, to type it all out again : there's a couple of things I can't find in Seashore…
1. LEVELS Histogram to adjust highlights, mid-tones, shadows
2. COLOUR BALANCE (not HUE) to adjust Cyan <> Red, Magenta <> Green, Yellow <> Blue for highlights, mid-tones, shadows
I'm a newbie but I've used image editors before and I'm surprised I can't find these. Maybe there's other ways to do them in Seashore? By the way, it's a lovely looking program, very user-friendly.