xkill on "Force quit" dialog crashes the whole session

[scrawl]

What I did:

Press X on a window that wasn't responding. Got tired waiting for the "Force quit?" dialog to show up. Ran "xkill" and pointed on the window.

What I expected to happen: the non-responding application is killed.

What happened instead:
Just before I ran "xkill", the "Force quit" dialog appeared, thus the xkill command ran on the Force Quit dialog rather than on the application window. Apparently, when xkill is invoked on a Force Quit dialog, a) the whole unity process is killed and b) the session crashes! (unsure why). The user is placed back to the login prompt, i.e. all open applications are closed resulting in possible data loss.

Possible fix:
a) Run "Force quit" dialogs in a separate process, or otherwise disassociate them from the unity process.
b) ?

Reproducibility: happens 100% of the time when running xkill on a "Force quit" dialog.

Description: Ubuntu 14.04.3 LTS
Release: 14.04

unity:
  Installed: 7.2.6+14.04.20151021-0ubuntu1
  Candidate: 7.2.6+14.04.20151021-0ubuntu1
  Version table:
 *** 7.2.6+14.04.20151021-0ubuntu1 0
        500 http://de.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     7.2.2+14.04.20140714-0ubuntu1.1 0
        500 http://security.ubuntu.com/ubuntu/ trusty-security/main amd64 Packages
     7.2.0+14.04.20140416-0ubuntu1 0
        500 http://de.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages