In testing Cinnamon builds, x11-wm/muffin-4.0.3 (which now lives in gnome-kit) has several issues. One issue is that it references a header file coming from gnome-extra/cinnamon-desktop-3.6.2, cdesktop-enums.h, which contains garbled, duplicated definitions starting at line 222. It appears that this was shipped from the cinnamon people this way. Removing this section (line 222+) resolves this issue.

The next build issue experienced is that muffin fails due to looking for cogl and clutter include directories in the wrong place, and is configured to build with all warnings treated as errors.

These two issues need to be resolved to move forward with testing and use of Cinnamon in Funtoo.