Moving a window beyond the top/left edge shifts the content

[kuwanger]

Moving a window's client area off the top of the screen shifts its client area to the right however far right the window is. Similarly, moving a window's client off the left side of the screen shifts its client area down however far down the window is. At ~50% right or down (respectively) the client area is blank/black. This occurs on Intel open source drivers, Nvidia proprietary drivers, and under Xephyr.

Description: Ubuntu 18.04.1 LTS
Release: 18.04

icewm-experimental:
  Installed: 1.4.3.0~pre-20180217-3
  Candidate: 1.4.3.0~pre-20180217-3
  Version table:
 *** 1.4.3.0~pre-20180217-3 500
        500 http://us.archive.ubuntu.com/ubuntu bionic/universe amd64 Packages
        100 /var/lib/dpkg/status