Gray shade overlay in dual screen setup

[elfuego]

Hi everyone,
You can see the effect I get when I activate second screen and set the screen positions in arandr. The system is 10 minutes old, fresh install of Xubuntu. Can anyone tell me whats causing this?

This was not an issue on the previous installation (normal ubuntu 12.04 + xfce) which I just wiped. If only 1 monitor is selected, display is alright. If both monitors are active and overlapping, display is alright. If I set the screen layout as it should be, its a shady-mess. :(

[elfuego]

Problem solved auto-magically by wiping xubuntu and installing lubuntu instead.

[I3roknI3ottle]

I was having the same problem with the gray shadow on windows when I enabled dual displays. I've resolved the issue by going to
Menu -> Settings -> Settings Manager click on Window manager tweaks -> Compositor --> disable "Enable display compositing".