Previously it was enabled only because of bug in libvirt. Now it is fixed (9e0e0224438b79073bf404627fed8e2889669374), so config needs to be updated.
@@ -29,6 +29,7 @@
{netdev}
{pcidevs}
<input type='tablet' bus='usb'/>
+ <video type='vga'/>
</devices>
</domain>