Comment 2 for bug 1597526

Rafael, I believe ~flexiondotorg has updated ubuntu-mate-themes (in ubuntu-mate-artwork) for GTK 3.20 since ubuntu-mate-themes are closely related to light-themes. I don't know if he's posted his work anywhere yet.

Please discuss your status with ~laney since he is planning to upload GTK 3.20 soon. See also this thread: https://lists.ubuntu.com/archives/ubuntu-desktop/2016-July/004816.html