Running Ubuntu 16.04 with the updates repository enabled, using the Nvidia proprietary driver 367.27.
A couple of days ago there was a Unity update (7.4.0+16.04.20160705-0ubuntu1) which includes a commit that causes graphical glitches/corruption on the background of Unity panel in my triple monitor (xrandr) setup.
The result differs depending on which monitor the Panel/Dash is opened on.
Specifically, on one monitor there is a horizontal offset on the background, on the second one there is garbage and on the third one there is no background at all, making Unity completely see-through.
Additionally, when transparent, the top bar is also affected.
After downloading the source code and compiling Unity from different commits, I have reached the conclusion that the commit which introduced the issue is #4145 from trunk (https://bazaar.launchpad.net/~unity-team/unity/trunk/revision/4145).
The following links demonstrate the issue, as well as show the exact point where the regression started occurring.
https://vps.tasossah.com/bugs/9c9f3d255d3c.jpg
https://vps.tasossah.com/bugs/c689e3866fff.jpg
https://vps.tasossah.com/bugs/unity_multimonbug.webm
Status changed to 'Confirmed' because the bug affects multiple users.