I am not sure why there is so little clear information in the net about the issue:
I just want to copy (drag and drop) files between the Ubuntu 16.04 host and the Windows 7 client.
I expected this as a basic feature. But it does not work.
Create a samba share on the host.
Since client and host should be able to communicate via a virtual network interface - automatically - this is a very easy workaround.
This worked for me. I think it will also work for you.
Download and install spice tool (
spice-guest-tools-latest.exe) on your guest OS (Windows 7/8/10).
Restart or shut down your guest OS (Windows 7/8/10).