It rejoins this idea
http://forums.omnigroup.com/showthread.php?t=9674
I don't like to have scrollbar in the tabs drawer, that kills usability. The flaw is when you have a long history in your tab. Scroll, scroll... no, no. I'll prefer a kind of shortcut à la exposé to browse my tab history (just a rough idea), something more temporary and non-intrusive.