Change the background of the Fedora logon Interface

After some necessary changes, I finally upgraded to Fedora17. However, the background of the new system looks uncomfortable. I want to change one. The steps are as follows: activities-> Applications-> System Tools-> System Settings-> Background, select your favorite image, and change it to another one. However, if you change the background of the desktop, the background of the logon interface remains unchanged. Okay, google, and find an article http://forums.fedoraforum.org/showthread.php? T = 265990. The procedure for www.2cto.com is as follows: 1. open terminal2. su3. xhost + // note that xhost is executed, and '+' is the parameter of xhost. sudo-u PGA launch-launch gnome-control-center5. click background and select your background the explanation of the 4th commands is as follows. When someone reposts the article, the command will be wrong without understanding the function of the command, the result is misleading (the poster is the victim). Here someone explains: www.2cto.com sudo lets you execute a command as if you had logged into a different user account. the-u option says which account, in this case the account is running-launch is the command that sudo is executing for you in the TPD account gnome-control-center is a parameter you are giving to launch-launch, it is another program that will be run (also in the AHP account ). all together, you type ONE command line just like this:
Note: The wallpaper that looks like the screen lock is still the old one. Author Hu Xiaohui