Just some comments below as requested
Isn't this debatable? Might someone want to see the errorbar range in
front of or behind a large marker with transparency? Why do you say
this with certainty?
You're right John. Personally, I think the default order should be for markers to be in front of errorbars, but on occasions I've wanted it the other way (the current implementation). I like your bouyancy idea. If you're after a different name, how about the more conventional "z-order".
It's so easy to do that I could implement it faster than I can
describe it, but I think buoyancy is a bad name (too hard to spell),
and I wanted to get some feedback on the idea. Should large numbers
be drawn last or first (last is my instinct, like list indexing, and
more efficient since you won't have to reverse the sort).
What is a
good attribute name? I think a method like scale_buoyancy would be
useful too so users wouldn't have to know the default values.
zorder or layer