Should someone else stumble upon this, the way to resolve issues for now is to not use gnome boxes, but rather remote-viewer and perhaps there's an issue with BIOS/EFI graphics setup with Windows 10 guests?
After a lucky coincidence, flickering seems to have be resolved for me while tweaking something else (OVMF NVRAM for EFI). It might have simply been manually updating OVMF or adding the NVRAM / VARS piece to my VM Win 10 guest config. I'm not sure. What I can report: * virt-viewer / remote-viewer, virt-manager and gnome boxes have have stopped flickering * virt-viewer / remote-viewer are now auto-adjusting windows 10 properly to the windows size * gnome boxes is scaling (zooming in and out) the Windows 10 display instead of auto-adjusting the guest resolution ** Unlike the Windows 10 guest, When I test a Linux VM with the spice agent installed, it auto-adjusts the guest resolution * virt-manager is not, it's simply cropping the output So I think something about how Gnome Boxes handles the Windows 10 guest is inferior to the way in which remote viewer does (when EFI is used, which does affect graphics setup). But perhaps wait till spice-agent officially supports Windows 10 with proper drivers, given you may not care for people like me who try their luck with the Windows 8.1 drivers in Windows 10. More detail on the EFI NVRAM issue? See: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1483071 Hacking around a debian/ubuntu distro specific libvirt apparmor bug allowed me to use a proper OVMF nvram template to the virtual machine config, and after reconfiguring the VM to use this, the display flickering stopped, so this may be something to do with UEFI simulation and windows 10 on KVM (but given my day job as just a virtualisation user, debugging that or understanding that low level interaction is beyond me). I shared similar info on a related bug where gnome boxes removed the ability to control scale and auto-adjust options for the spice display behaviour https://bugzilla.gnome.org/show_bug.cgi?id=729700 ** Bug watch added: GNOME Bug Tracker #729700 https://bugzilla.gnome.org/show_bug.cgi?id=729700 -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1479717 Title: Auto resize VM doesn't work with windows 10 guest Status in QEMU: New Bug description: I,m using a Ubuntu 15.04 host and a windows 10 guest (both 64 bit) on a intel i7 proc. My ubuntu system is up-to-date and I'm using QEMU emulator version 2.2.0. I use virt-manager 1.0.1 and SPICE guest tools 0.100 are installed on the guest. With the exactly same setup and a windows 7 guest I can set "Auto resize VM with window" and it perfectly works. After installing SPICE in windows 10 I can still select this box, but it doesn't work any longer. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1479717/+subscriptions
