Created attachment 503256 [details, diff] ncurses-6.0-remove-an-early-return-from_nc_do_color.patch ncurses 6.0 contains a bug that was fixed upstream in patch 20151017. It fixes miscoloring issues in nano when using custom UI colors or syntax highlighting. The attached patch applies cleanly to the ncurses 6.0-r1 package in portage.
i think things should be fixed w/ncurses-6.1 which is stable now