gnomeradio uses the in gtk 2.4 deprecated gtkcombo widget and defines -DGNOME_DISABLE_DEPRECATED -DGTK_DISABLE_DEPRECATED \ -DGDK_DISABLE_DEPRECATED -DG_DISABLE_DEPRECATED so it fails to compile
Created attachment 33394 [details] updated ebuild
just use sed -i
fixed, although a bit different than you do. also added a fix for gcc34 compilation. Thanks for the report.