Hah... you don't believe to Santa, but believe to ONE OS everywhere?? Dude, time to grow up! Hardware is SO different and we have so different tasks on 'em that declaring one OS is obvious stupidity. One poor guy already tried to be "everywhere" - his corpse with tag "Java" on the foot still remembers us don't sit with one a_s_s on two chairs. Smartphone requires separate, compact OS with only libraries which make sense + mobile only stuff (like gyroscope, Wi-Fi, 3G, Battery, etc) + very "mobile specific" UI. Desktop is different and has no limits. Nadella thinks if phone and desktop have Button, that's it! One universal button fits all :) In reality his ugly _mobile_ buttons are horrible on desktop and nobody will enjoy using it. End of story and end of MS.