I'm also being hit by this bug, any progress? I just upgraded from 12.04 to 14.04 and decided to try out KDE. I have 3 monitors, my left two are X1 and my right most is X0 (primary). When I lock the screen, X0 locks (but the password box appears halfway off the right side of the monitor, as if it was a screen spanning 2 monitors) and the other two still display whatever was on my screen at the time.
I'm also being hit by this bug, any progress? I just upgraded from 12.04 to 14.04 and decided to try out KDE. I have 3 monitors, my left two are X1 and my right most is X0 (primary). When I lock the screen, X0 locks (but the password box appears halfway off the right side of the monitor, as if it was a screen spanning 2 monitors) and the other two still display whatever was on my screen at the time.