Tooltips are washed out and for practical purposes unreadable

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=15.10
DISTRIB_CODENAME=wily
DISTRIB_DESCRIPTION="Ubuntu 15.10"

---

shutter:
  Installed: 0.93.1~ppa1~ubuntu15.10.1
  Candidate: 0.93.1~ppa1~ubuntu15.10.1
  Version table:
 *** 0.93.1~ppa1~ubuntu15.10.1 0
        500 http://ppa.launchpad.net/shutter/ppa/ubuntu/ wily/main amd64 Packages
        100 /var/lib/dpkg/status
     0.92-0.1ubuntu1 0
        500 http://us.archive.ubuntu.com/ubuntu/ wily/universe amd64 Packages

---

I expect the tooltips to follow the system theme - white text on a flat dark background.

Tooltips instead are white on an off-white 3d-ish background.

*Note: I noticed that the tooltips were also washed out on a version of OpenSuse; this is not confined to Ubuntu systems.