I'm unable to modify the keyboard shortcuts for switching workspaces in Ubuntu 14.04 Desktop running in VMWare Fusion 6.
The host uses CTRL-ALT <ARROW> to switch spaces, so I want to rebind the VM to use CTRL-CMD(WIN) <ARROW> for switching spaces and CTRL-CMD-SHIFT <ARROW> for moving a window to a new workspace.

As soon as I press the CMD (WIN) key in the guest VM, the shortcut changes to "Disabled". Any ideas?