Steps to reproduce:
1) Open SwingSet2
2) Go to JFileChooser demo.
3) Click on "Show Plain JFileChooser"
4) Keep clicking on toolbar icon "Up One Level" till you reach root
5) Now notice, Button is disabled, But still it uses the same image which it
   uses when it was enabled.
Using gray image when button is disabled will give good disabled effect, as
complete button will look disabled, Unlike now where you still have colorful
image in a disabled icon.

This can be reproduced in tiger b43 and all the themes of Metal L&F including
new ocean L&F