I did not notice until I recently changed my wallpaper, but there seems to be a thin line (maybe 1 pixel) between the unity launcher and a maximized window (see attached screenshot). This problem appears with any application. Launcher opacity is obvisouly set to 1.
I already activated/deactivated sticky edges without any effect. This effect is also visible using sticky edges with a non-maximized window.
Any ideas what could cause this problem?