If you’re one of those who aren’t crazy about the default background that comes with Mission Control, Dashboard and other parts of OS X Lion, following is an easy way to change to something more to your liking.

You have to drill down a bit into your system where CoreServices is hiding, where OS X keeps many of its invisible apps. In order to change the background, you only need to find Dock.app, which is here:

/System/Library/CoreServices/Dock.app

Right-click on Dock.app, then choose Show Package Contents. Now you just need to dig a little deeper one more time to find the default background image:

/Contents/Resources/defaultdesktop.png

Rename it to defaultdesktop-old.png, then save another 256×256 patterned image as the file name you just replaced, defaultdesktop.png. And remember, for it take immediate affect, you’ll need to open a terminal and type:

killall Dock

Then exit the terminal and you’re good to go.

Additionally, if you would rather use a non-repeating image, and instead use a regular desktop wallpaper, you can do that also. Again, rename defaultdesktop.png, but this time don’t replace it. Head back, instead, into the CoreServices directory where you started when you were locating Dock.app, and replace DefaultDesktop.jpg with one you like. You can do the same thing with the Dashboard background by replacing the file named pirelli.jpg. Cool!

(Via: Lifehacker)