I have recently noticed that for instance if I open the System Monitor and have it so that it takes up half of my screen on one of the sides the top divisory line looks normal like this: System_Monitor_Screenshot1.png

However if I then switch to the "Processes" tab this happens: System_Monitor_Screenshot2.png

Then if I drag the window to the top of the screen and make it go fullscreen that way then the line disappears entirely: System_Monitor_Screenshot3.png

And then if I go to the "Resources" tab the line becomes only in the centre and in a strange pattern off to the right in some cases: System_Monitor_Screenshot4.png

Finally, if I I drag it away anywhere it becomes normal again.

I initially filed a report on this issue here but thought I should also do so upstream: https://bugs.launchpad.net/ubuntu-gnome/+bug/1539289

---

OS Information:

    No LSB modules are available.
    Distributor ID: Ubuntu
    Description: Ubuntu 15.10
    Release: 15.10
    Codename: wily
    Flavour: GNOME
    GNOME Version: 3.18

Package Information:

    gnome-system-monitor:
      Installed: 3.18.2-1~wily1
      Candidate: 3.18.2-1~wily1
      Version table:
     *** 3.18.2-1~wily1 0
            500 http://ppa.launchpad.net/gnome3-team/gnome3-staging/ubuntu/ wily/main amd64 Packages
            100 /var/lib/dpkg/status
         3.16.0-2 0
            500 http://archive.ubuntu.com/ubuntu/ wily/main amd64 Packages