As thge summary states.
I am also having trouble using the gtk backend with matplotlib under Gentoo. The ebuild fails to detect the installed gtk+ module. Can anyone solve this?
I tried to unbundle it using the fedora patches (see ebuild) but some test fail. Probably this can be fixed. agg-2.5 doesn't seem to be too different fromt the bundled version though.
The diff between agg-2.5 and bundled agg and is huge, lots of them in include/ are code additions. It is not a copy but a de facto fork.
I don't think we could unbundle agg from matplotlib with a simple patch, unless upstream intends to.