The new Fedora 18 Linux distribution has the Power Off option available in the user menu by default; negating the need to install an add-on from extensions.gnome.org to add this functionality. This is a very good addition to the new Fedora distribution. According to this blog linked here: http://www.dedoimedo.com/computers/gnome-3-6.html. There are other problems with the Fedora 18 Linux distribution like a strange new web browser that is more akin to a kiosk browser than the current incarnations of Firefox and Chrome that we are used to at the moment. A very strange system; they seem to be removing more and more functionality as they go; soon the whole Fedora desktop will be like a mobile interface like IOS instead of a fully functional Linux desktop like the superior KDE 4.9 interface that I am using as I type this. The whole distribution seems to be entirely cloud oriented with your documents loaded from on-line services such as Google Drive. But they should show the empty local ~/Documents folder by default instead of defaulting to pulling documents from the cloud. I have not gotten Gnome Shell working properly with Linux Mint; but I am sure that Mint would not default to cloud storage.
Cloud storage is all well and good; but what if your Internet is down and you need to access your documents? I guess if you use Ubuntu One; you would have local copies of the files that have been copied to cloud storage. As you can see in the screen-shot to the right; this is what the Fedora 18 Documents folder look like. Surely they could have made the local folder the default and given you an option to have cloud storage if you have on-line accounts that would plug into Gnome to enable this functionality. The Fedora 18 distribution will ship with the MATE desktop; so installing that would be a good way to get a more usable desktop interface. That way you will not have to use the buggy and error prone Gnome Shell desktop in Fedora. Better to install Linux Mint instead if you want a reliable and usable Linux desktop.