This still happens in Raring, for me. When I lock the screen, only one blanks, and the other remains showing what was on it before locking. Using an input device (mouse jiggle, tapping shift key on keyboard, etc.) while locked works around this.
I originally filed this as bug 960073 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/995387 Title: In dual monitor conditions, the 'lock screen' can expose portions of users desktop To manage notifications about this bug go to: https://bugs.launchpad.net/compiz/+bug/995387/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs