How to switch between virtual machines that are in fullscreen mode?

Solution 1:

When inside a VM, you can achieve your goal by:

  • hitting the Host key (Win: right Ctrl by default, OSX: Command; you only need a single key press)
  • Then using Alt Tab

tested on VirtualBox v. 4.3.8 (one monitor only)

The Host key, once pressed, makes the guest loose focus in favor of the Host. Then you can use Alt Tab the usual way.