To see this, create a custom bld installer and launch it. After selecting Setup Type (Recommended, Custom), click Next button to get the dialog box for Quick Launch. ==> The image in the middle of the box is covered with black rectangle. Observed in 3/4 CCK and Factory blds.
Adding a few more to cc: list
This was bugscape bug 12382 in the browser. Its been marked fixed as of today's build so we shouldn't see it in the next CCK and Factory builds.
Browser bug - fixed in underlying client of 3/11 CCK bld.