gentoo-overlay/gnome-extra/gnome-color-manager/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
	<herd>gnome</herd>
	<use>
		<flag name="packagekit">Enable support for the distro-neutral package
			manager GUI <pkg>app-admin/packagekit</pkg></flag>
	</use>
</pkgmetadata>