You can now make individual Windows apps use OS X full screen with parallels using a key-combination. When the windows application is active press CMD-CTRL+F and finally it’s using OS X full screen and you can set it in mission control and 3-finger swipe between them( the outlook window in the screenshot is a windows app in coherence mode ). Instead you can use the view menu to switch in/out of individual applications.
This solves problems for many people who were not satisfied with what they used to do. When using coherence mode so that you run windows apps and OS X apps seamlessly side by side, but when Lion came out with the OS X full screen mode and then mountain Lion made it useful, you can use the full screen mode for certain OS X apps but not an external screen as it makes the most of many screens.
With all this, still you cannot quickly figure out how to make Windows apps go OS X full screen and then be visible in Mission Controls still got the taskbar at the top and couldn’t 3-finger swipe between them also a maximized Windows application covered over OS X apps on primary desktop so you have to tab around to find it, thus making a windows application use OS X full screen mode when using coherence Mode in parallels the best way.