When scrolling up using arrow keys or mousewheel, the bottom few pixels of the welcome message notify bar are left 'trailed' on the screen. Moving over certain elements refreshes these areas (i.e., logo and 11m ago). If I scrollwheel fast enough, the space between the glitches increases. This happens on any Stack Exchange site with such a welcome message that I haven't clicked [x] on, logged in or out. I've finally just registered so can't advise on the notification bar's other uses (or directly post a screenshot).
I'm using Chromium 17.0.946.0 (Developer Build 110888 Linux) Built on Ubuntu 11.04, from https://launchpad.net/~chromium-daily/+archive/ppa but I'm sure this happened in Chromium 15 before I moved from Ubuntu to Arch.
This could be an on-going Chromium bug, but I thought I'd try report it here first. Thanks.