The 4.0.1 PatternSkin
had a color gardient on top that highlighted the topic action tabs on top. The current skin has white tabs on white background, which makes it somewhat hard to see. I suggest to color the tabs lightly, see screenshot before and after.
The 4.0.2 pattern skin also has the same gradient.
If you make the buttons yellow as suggested you get yellow buttons on yellow background.
I have the feeling you have not upgraded your Firefox to 1.5.
The earlier versions do not show the gradient properly with areas defined by DIV. The earlier versions also had problems with the left bar width in 4.0.1.
We should take not to fix something for an old browser version and mess it up for the current versions.
Discarded in agreement with Peter and Arthur