The picture above is a screenshot from Mission Control showing the desktop and full-screen apps. The problem is that I want a different arrangement. I want the order to be Safari-Desktop-iTunes. I can't drag the desktop between Safari and iTunes apps, and when I drag Safari to the left of the Desktop, it goes back to its original place. So how can I modify the place of the Desktop? (I want to use only one Desktop, I know that it is possible when other Desktops are added) By the way I'm using Mountain Lion.
As far as I know, mission control is set up in such a way that the dashboard and the first desktop are immutable (i.e. cannot be changed). There might be a flag or something for it somewhere that you could disable that behaviour, but it would definitely require some serious digging since it's part of how mission control is written.