Example project crashes when unplugging the external screen

**Setup**
Windows 10 notebook with one GPU
External monitor connected by HDMI or by docking station (set as primary screen)

**Observed behavior**
The GLWpfControl.Example project crashes with an UCEERR_RENDERTHREADFAILURE exception when I unplug the external monitor or a dockingstation with an external monitor connected.
See also my comment on #30.