If the gconf-key /apps/gwd/blur_type is set to "all" or "titlebar" the rendering of the decoration gets messed up. While these two settings are probably only meant to blur the decoration/window-frame or the titlebar actually the whole region of the decoration gets blurred (the drop-shadow part) or not properly refreshed. It is most evident if you move a gnome-terminal window over an evolution-window, while the gnome-terminal window is partly over the desktop and partly over the evolution-window.
Experienced on Ubuntu 6.10 running on a GeForce7900GT using the 1.0-9755 driver.
Created attachment 9116 [details]
example screenshot of drawing-flaw
A small screencast of the artifact in action can be seen here:
http://macslow.thepimp.net/clips/compiz-decoration-glitch.ogg (ogg/theora, 1.5 MB)
It's visible on the right side of the window at the beginning.
Yet another view of the drawing-artifact:
http://macslow.thepimp.net/clips/compiz-decoration-glitch-2.ogg (ogg/theora, 1.4
Watch the right and bottom edges of the terminal-window while being moved.
This bug should be fixed now.