I started noticing this a while ago and it has happened enough times that it seems to be a real issue. I usually leave Parallels with Windows 10 running full screen on my 12" MacBook while most commonly leaving the screen on the Mac desktop. When I leave from work for the day I put my Mac to sleep... When I get home & switch over to windows, the resolution appears to revert to a non-retina state. This leaves my screen looking like this when I switch over: If you zoom in you can see that in addition to the icon that is twice as big as it should be, the desktop picture is showing at half its resolution: I end up having to switch out of full screen mode, then back into it. After that things go back to normal: And when zooming in after that: While it's not a major problem it is an annoyance. For whatever reason every time I try to fix the issue I end up in coherence and can never figure how to get back out again.
I am seeing the same issue. After Retina (el capitan) goes to sleep, resolution for Windows 10 is broken, needs to have the VM rebooted to fix it. Its an issue with parallels for sure. I am confident if anyone else tests it, will produce the same issues.
