Hi there. If, like me, you have also been experimenting on a laptop (in my case this is an HP Envy running Windows 8.1 64 bit), you may have encountered issues with not having any options to change the screen orientation. There is a registry fix that worked for me, so I'll post the changes here. The usual disclaimer about backing everything up and changing at your own risk blah blah applies 🙂
So change this key: HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\4D36E968-E325-11CE-BFC1-08002BE10318\0001