bug#4326: 23.1.50; Emacs.app leaves a residual line on the display

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

GNU Emacs 23.1.50.1 (i386-apple-darwin9.8.0, NS apple-appkit-949.54) of
2009-08-10 on neutron.local

1. Open w3m that uses tabs in the header. Any package that uses the
   header will be able to demonstrate the problem, for example, info.

2. Quit w3m

You will see right under the titlebar, there is still a line, a few
pixels high. That line was part of the header and it didn't disappear
when the header was removed. See the attached a screenshot.

Original:


Zoom in:



Leo