Hi,
The project drawer usually responds to horiontal scroll wheel moves, which is of great aid when you're working on a sub-sub-sub-sub dir and still trying to fit the editor in an ibook screen.
When a vertical scrollbar appears, though, the horizontal scroll whell stops working.
I suggest that you either a horizontal scrollbar is added when needed, or that the drawer always responds to the horizontal scroll wheel, even when the vertical scrollbar appears.