Regarding UI changes, minimalist Window Managers and Desktop Environments for *nix tend to work like that. They stick to their base paradigms and rarely, if eve

Regarding UI changes, minimalist Window Managers and Desktop Environments for *nix tend to work like that. They stick to their base paradigms and rarely, if ever change, once considered stable. XFCE has been already been mentioned. But Openbox, dwm, awesome, etc... all could fit. Note that it's expected, and assumed, that the user can switch to these more conservative UIs if they prefer, even if the base distro defaults to only one.