As of an update from a few days ago, users are now able to access a graphical user interface for editing xorg.conf, though only for graphic and display settings. This tool has support for dual monitors at the moment, and with the release of X.org 7.3 it will be possible to add even more. You can turn on and off both (or one) of your monitor(s), change the available resolutions, orientations, and set mirror or exteneded desktops. Fosswire
Typical, I finally get to the point where I can edit the file without ending up at the terminal in panic mode, and they make it easy.