http://bugs.winehq.org/show_bug.cgi?id=11252
--- Comment #3 from Dan Kegel dank@kegel.com 2008-03-18 15:26:14 --- Created an attachment (id=11481) --> (http://bugs.winehq.org/attachment.cgi?id=11481) Screenshot of one-pixel-wide blemish
Hmm. It's repeatable, but it doesn't involve dual monitors, sorry for the bad description.
To repeat: on a single-monitor system, show the Navigator window. Then drag the navigator window a centimeter or so in any direction. You will see one-pixel-wide artifacts on the navigator at the previous location of the navigator's edges.
It seems to be the window-motion-outline visual effect going awry.