> An user interface which takes lots of vertical space which is at premium instead of being on the sides which are much less used, "PROPER testing"? Somehow I doubt it!
The MSOffice201x ribbon actually takes less vertical space than LibreOffice's menu plus two (or three, in some cases) lines of toolbars. It is also spatially better distributed, and the size relations between the icons reflect their "use count" in user testings. See Deborah Hix's usability works... IIRC lateral toolsets have a problem because the distance the mouse has to travel is bigger. Anyway, people who do a lot of DTP or other "give me my vertical space" application IME make use of a rotated display, whenever possible!
> Speaking about failure, I remember the Gnome's decision to use "spatial browsing" which was backed supposedly by usability research, they had to revert it in the end.
I have heard those rumors, but I have never seen any real research.