Thanks for the tip, but I have already done that. It didn't change anything.have you installed vmware tools in your VM? there's a menu item to install that.
...Any thoughts on why this is so and how to solve this?
(in a Terminal window)sudo nvram boot-args="rootless=0 kext-dev-mode=1"
@Sandbox: Does this happen, if you select an older hardware version in the VMware Fusion preferences? I suspect that the older VMware Tools are not compatible with the newer (virtual) hardware.
If you are not using the current VMware Fusion Technology Preview 2015 then this is easily explained: Fusion does not officially support OS X El Capitan nor Windows 10. They do run but there are issues. See community.vmware.com for more info about this and the download for the tech preview that does have official support for both operating systems.
No I did a fresh install of the tech preview on 10.11 after finding that the normal version, 7.1.2 IIRC didn't work.Did you upgrade from a previous Fusion version to the tech preview? If so, how did you do the upgrade and did the Win10 vm already exist in the previous version?
This is what i did regarding my 10.9.x, 10.10.x and 10.11.x VMs. VMsvga2 allows more resolutions than the standard OS X or VMware driver.
That did the trick. Uninstalling vmware tools, shutting down the VM, starting it back up and reinstalling vmware tools.That might be the reason why it is not working. Officially you need to uninstall the VMware Tools, shutdown the vm and then proceed with upgrading Fusion. Usually not doing that works out fine but sometimes you get these strange issues with VMware Tools. Uninstalling Tools, rebooting and then reinstalling might work. There doesn't seem to be any topics about this issue on the tech preview forums at vmware.com. I'll see what happens with my Win10 vm.