Created attachment 404544 [details, diff] spice-gtk-0.28.patch spice-gtk >=0.27 is required for gnome-boxes for Gnome 3.16. We have this bump in the gnome overlay with additional changes to support other python implementations but it depends on patches to support nested variants in multibuild. In the meantime, this patched ebuild proposes the following changes: * allow build gtk2 or gtk3 support only * allow build no gtk binding, not sure if it would be any useful but it works, if not wanted, a REQUIRED_USE condition will fix it. * use of multibuild to simplify ebuild logic, the ebuild was based on early work I did in gtk-vnc to support building both gtk2 and gtk3 versions in a single ebuild but things have evolved and I find multibuild use quite convenient here and it requires little changes if the ebuild needs to support multiple python versions in the future (check https://gitweb.gentoo.org/proj/gnome.git/commit/net-misc/spice-gtk/spice-gtk-0.28.ebuild?id=ad82653641cca1914c2e2ff0867d911e28cefcaa for this). I will move this bump to tree this weekend if there is no objection and track down ebuilds that need to [gtk2(+)].
Ended up using a slightly different patch not adding gtk2 control since I do not have time to chase ebuilds using this yet.