If you have just upgraded to Snow Leopard, you might have noticed that the Expose in Snow Leopard, displays a hideous blue border when you hover/highlight on top of a window.

While as of right now, there isn’t a way to change the color manually. You can change the border to transparent.




Here’s how to do so?
1. Grab this zip file. Copy these two files - expose-window-selection-big.png” and “expose-window-selection-small.png”

2. Go to Macintosh Hd/System/Library/Core Services

3. Right click the Dock.app and click Show Package Contents

4. Go on the Contents Folder and then the Resources Folder

5. Find the two files named “expose-window-selection-big.png” and “expose-window-selection-small.png”. Copy them somewhere else to keep as a backup just in case you want to revert to the blue border.

6. Paste the files you copied in Step 1.

7. Restart your Mac.

8. If you followed all the steps correctly, you should now have the a transparent border when you hover over objects in expose.

(This tutorial is based on a thread from the MacThemes Forum)