Depending on mutually exclusive on cinnamon-1.4 # grep -n gnome-base/gnome-menus /usr/portage/gnome-extra/cinnamon/cinnamon-1.4.ebuild 54: >=gnome-base/gnome-menus-3.2.0.1-r1:3[introspection] 102: gnome-base/gnome-menus:0[python] without gnome-base/gnome-menus:0 cinnamon work correctly
cinnamon-menu-editor requires the old gmenu python module, which is only installed by slot 0 of gnome-menus. Slot 0 and slot 3 of gnome-menus (for example, gnome-menus-3.0.1-r1 and 3.2.0.1-r1) are not mutually exclusive, and can be installed in parallel on the same system.