Reporting this as a matplotlib bug because that's where I see the error.
I have some code which was running fine, drawing a scatter plot with transparent/alpha for the colour, like this...
This used to draw a very faint transparent series of points which (where there were a lot of points) built up a fairly solid colour. Now, after an upgrade to Ubuntu 9.10 I see only solid colour, no transparency/alpha at all. Also (a different problem), I get an error message (when adding a legend, that no labels were defined). This is also changed behaviour since the upgrade. Seems like scatter has changed... but why?
I tried downloading matplotlib source code and compiling -- and despite a few glitches (like, it was by default Mac compilation) -- I think I got that going OK. Still, I see exactly the same behaviour. Scatter is behaving differently, and I really need that alpha/transparency!!!
Neither of these problems were evident on Ubuntu 9.04, and I was using the inbuilt matplotlib for that.
Please excuse if this report is in the wrong place -- my first attempt to report a bug in this package.
Andrew 'Boo' Davie