I have moved from Snow Leopard to Mountain Lion OSX 10.8
Mountain Lion’s Security is tight as it has feature of allowing genuine apps from Mac App Store & disallowing Pirated apps from anywhere.
I was installing Inkscape & GIMP on Mountain Lion OSX 10.8
I was confused that Inkscape & GIMP was not working on 10.8 as it was just not opening…
Then after clicking on X11.app in Application’s Utility folder I come to know that X11 is not preinstalled in OSX 10.8
You have to download it with XQuartz App from Here.
Now I have installed & using all Genuine & OpenSource Applications on my Macintosh.
Thanks & Regards