One of the welcomed new feature of 10.9 is better support of dual monitor the kind of set up that people need in a work environment with Windows network. Before 10.9 your extended desktop is either all OS X or Windows. It’s not inconvenient a 3 fingers swipe will switch OS within a blink of eyes.
With new 10.9 you could have each of your monitor to display the OS you want independently, it’s supposed to work that way.
I upgraded my 2 MBP’s flawlessly, have done this over the years many times, I was so confident that I didn’t even bother to do backup first.
I have Windows updated to 8.1 in my work MBP before moving OS X up, as I need it for work I expected everything to work normally. The advertised 200 new features I never cared.
Unexpectedly new feature turned bad on me, the dual monitor feature broke down completely after the OS X update, I just can’t extend the Windows desktop which I needed for work! Windows still detected the second monitor but OS X occupied it, Windows as an app can be full screen but it didn’t have control over the second monitor.
Naturally I googled for a solution didn’t get much useful links as this may be pretty new. I assumed this sort of setup must be very common for people at work. The culprit must be VMWware Fusion which launched a new version 6 ahead of OS X and 8.1 upgrade hitting the street.
Within minutes and $49.9 for Fusion 6 licence I have two OSs independently on 2 displays. When I clicked the Windows display the second display will smartly switch to my windows extended desktop from OS X. 3 fingers swipe works the same on both display.
The formula is 10.9 + 8.1 + 6 = magic I want.