Re: kernel 4.12.0-0.rc0.git7.1.fc27.x86_64 no mouse in a Virtualbox vm
Rawhided kernel 4.12.0-0.rc0.git7.1.fc27.x86_64 works fine using VMware WS VM thus I conclude that the problem was with the Virtualbox guest additions which I did recompile. If compiiling the guest additions does not fix the problem I'll post to the Virtualbox forums.
The real "back to future" is with the Rawhide kernel developers since kernel 4.12 does not yet appear on kernel.org. But things like this have happened before.