Unity top panel background
Change the Unity top panel backround gradient to fit with maximized windows, where is the application has a menubar (e.g. OpenOffice.org, LibreOffice... etc.) or the top of the application has a dark grey part (e.g. Chrome/Chromium, Firefox... etc.).
I think the perfect solution for this problem, is that to change the gradient to exactly the same what the (unmaximized) window border have in Ambiance/Radiance theme.