There are USE flags in use.desc and us.local.desc, which do not show up when emerging seamonkey. Reproducible: Always Steps to Reproduce: 1. emerge -pv seamonkey 2. grep seamonkey /usr/portage/profiles/use.* Actual Results: [ebuild R ] www-client/seamonkey-2.12.1 USE="jit* webm -alsa -chatzilla -crypt -custom-cflags -custom-optimization -dbus -debug -gstreamer -ipc -libnotify -roaming -startup-notification -system-sqlite -wifi" Differences in flags... "seamonkey" (use.desc) does not show up in the emerge output "composer" "mailclient" and "methodjit" (use.local.desc) do not show up in the emerge output 1) "methodjit" has probably been replaced by "jit" 2) In addition to seamonkey, the "webm" USE flag is available for... mail-client/thunderbird www-client/firefox www-client/torbrowser While cleaning up the seamonkey flags, maybe consider making "webm" a global flag.
They are included via metadata.xml Please refer to package location.