For USE="sourceview" the DEPEND in the anjuta ebuild specifies that the plugin needs at least gtk+-2.10, but along the deps some lines up it says that anjuta itself needs gtk+-2.14 so that line can be removed. Also the sourceview have no problems building here even without libgnome installed on my system.
+ 24 Jan 2010; Gilles Dartiguelongue <eva@gentoo.org> -anjuta-2.24.1.ebuild, + -anjuta-2.26.2.0.ebuild, anjuta-2.28.1.0.ebuild: + Dependency cleanup, bug #301842. + Fixed without a bump, thanks for reporting.