Just to keep you up to date on what I have discovered.
Xen was broken on F27 and F28.
https://bugzilla.redhat.com/show_bug.cgi?id=1486002#c36
I now have Windows 10 running under Xen 4.11.0-7 on F29 !
But F28/29 on Xen seems to have a problems with continual window refreshing probably something to do with Wayland.
I am going to try Xen on F26 which is version xen-4.8.1-2.
Regards,
Aaron