Wrong input coordination on HiDPI with VirGL

(Was filed at https://github.com/virt-manager/virt-manager/issues/117 but later discovered it's more a spice-gtk issue)

On a HiDPI display (2x in my case), using VirGL (virtio-gpu), it seems that the mouse input coordinate is wrong when the virtual screen size does not match spice widget size. The virtual screen shows up in the middle but takes input with an offset.

Here is a screencast with spicy: Peek_2020-06-06_14-36

OS: Arch Linux Component versions:

virt-manager 2.2.1-2
spice 0.14.3-2
spice-protocol 0.14.1-1
spice-gtk 0.38-1