Hi there!
I just found a bug: if you don’t specify a color for an error bar (in my case using go.Scatter) the opacity parameter has no effect, and my error bars stay unbearably opaque.
I’d like the error bars being the same color as my scatter plot, but very transparent, in order for them not to perturb the readability of my graph.
My report is due tomorrow, so don’t bother rushing. 
Otherwise, I love plotly! Thanks a lot for everything!
Oh, and a feature request: printable colors! It would be nice to have a boolean setting in go.Layout, like ‘black_and_white’, that would cause the lines and the fills to vary in shape instead of colors. You know how it is very important to make your paper readable on printed B&W in academia, so I think this would be very useful for many of us.
Bye!