Great feature. However, as Aliji said, it does not work with the new version of Gmail. It seems the fix would be simple enough, looking at the code, however, I do not know the innards of Gmail vs Gmail 2.
The best design eye I've seen for GMail 2.0 so far, and, as you said author, still needs a lot of work.
One particular issue that is a deal-breaker for me: Chat windows, including profile mouseovers on the side, are transparent, and show everything that is underneath them, which is usually some part of the inbox, rendering chat completely unusable unless you "pop out" chat windows every time.
Also, the inability to distinguish between a chat person's name and their status is very troublesome.
Other things that need to be fixed: - Difference between read and unread messages in the inbox need to be more distinct. - Unstarred messages look brighter than starred messages. Darken the unstarred (and fix the terrible aliasing around the starred messages). - Tighten up the space between the top search field and the Compose Message link, and everything below it. That space at the top has been totally abused by Google. Should be eliminated completely. - Suggest removing the "grid" background image. It's kind of cheesey. Perhaps make the background color itself slightly lighter.
About GMail Remove Top Left Padding on Dec 03 2007
About painted black - google + gmail (ALL) on Nov 19 2007