Virtualbox Manager Crashes when moved to 2nd monitor on Linux Host.

[mop]

Running Ubuntu 16.04 (fully patched), and when I attempt to move the window for the Virtualbox Manager to a second physical screen, the Manager crashes with various segfaults. The Manager does NOT crash if moved to a second desktop workspace on the host (and the VM starts just fine). The Manager also does NOT crash if I simply mirror the primary display (which I'll have to use for my current workaround.

Basically, no matter what I attempt, when I move any Virtualbox (6.1.0 and 6.0.14) window to a different physical screen, there is a segfault. Some dmesg output is pasted here:

[ 2668.255651] VirtualBox[21052]: segfault at 7ffd96641fe8 ip 00007fc21b9932b6 sp 00007ffd96641ff0 error 6 in libQt5GuiVBox.so.5[7fc21b86b000+5f3000]
[ 2673.511188] device vboxnet0 left promiscuous mode
[ 2673.538944] vboxnetflt: 0 out of 69 packets were not sent (directed to host)
[ 2949.375093] vboxdrv: 0000000000000000 VMMR0.r0
[ 2949.584145] VBoxNetFlt: attached to 'vboxnet0' / 0a:00:27:00:00:00
[ 2949.584944] device vboxnet0 entered promiscuous mode
[ 2949.687535] vboxdrv: 0000000000000000 VBoxDDR0.r0
[ 2949.829857] vboxdrv: 0000000000000000 VBoxEhciR0.r0
[ 3447.396061] VirtualBoxVM[22573]: segfault at 7ffe8e46fff8 ip 00007ff3849896f2 sp 00007ffe8e470000 error 6 in libQt5WidgetsVBox.so.5[7ff3846e7000+676000]
[ 3462.001978] vboxdrv: 0000000000000000 VBoxDDR0.r0
[ 3462.149045] vboxdrv: 0000000000000000 VBoxEhciR0.r0
[ 3499.044449] VirtualBoxVM[23316]: segfault at 7fff4881fff0 ip 00007f9c9fa39c29 sp 00007fff4881ffc0 error 6 in ld-2.23.so[7f9c9fa26000+26000]

[janitor]

#19204