Canvas extension color: transparency?

[chefranden]

I watched a Deke Mcclelland tutorial about the content aware scaling in CS4. As part of the tutorial he enlarged the canvas size. His canvas extension color was grayed out in the dialoge box and the extension color opened as transparency. How did he do that? I can't figure it out.

 

[chefranden]

I figured it out.

First change the background layer to a layer by double clicking and renaming it. Then enlarge the canvas and it extends as transparency. Thanks for any work you might have put in to figure this out.