Please update media-gfx/nomacs version to 3.4.0, that was released July 22, 2016, thanks. http://nomacs.org/nomacs-3-4/
Thanks, fixed in git. https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=95d16c4f50c3fdb99ddd4aaa333dc81a5b436fe9