Windows 7
(With previously addition of nonupdated customui and nonupdated nodeeditor, and CommandBar Mod.)

Installed V4_18, leaving V4_12 installed.
In V4_18, saved ui/CommandBar.htm, and copied modded CommandBar file from V4_12. (Modded for customui.)
Copied ui/customui to V4_18.
Tried to copy ui/nodeeditor, but failed to do so. Administrator setting may interfere with copying. Mine are a bit relaxed, permitting copying, but making it harder.
(Later copied ui/nodeeditor.) (Folder copied to, must not be open, I think.)
Copied all of the _scripts.js and _scripts.htm to Command folder. (Command folder must not be open)
Used Windows Control Panel to uninstall V4_12.
V4_12 is now gone, except for _scripts, ui/customui, and ui/nodeeditor, and previously saved CommandBarSaved file(s).

- Brian

ps Not sure if I need to locate an old V3 file to revert the fonts?

(Michael, please delete post if it is incorrect, or too confusing... :-)

Note, nodeeditor 0.97 now has menu icons...