When using a virtual machine in VirtualBox you might want to switch to a different console by hittingCtrl+Alt+F<n>
where <n> stands for the number of the console you want to access (like Ctrl+Alt+F1 to get a text console and Ctrl+Alt+F7 to get back to your X session).
Unfortunately, key combinations with Ctrl+Alt like the mentioned Ctrl+Alt+F<n> or Ctrl+Alt+Del will not be sent to the guest operating system. Instead, Ctrl+Alt+F<n> will only let you change consoles on your host and Ctrl+Alt+Del will magically disappear and effect neither the host nor the guest OS.
VirtualBox offers two menu entries (under the menu entry “Machine”) to send Ctrl+Alt+Del and Ctrl+Alt+Backspace to the guest OS, but does not offer such a feature for other key combinations.
Fortunately, you can use the host key (the right Ctrl key by default) as a substitute for Ctrl+Alt. Therefore when pressing
VirtualBox will sendCtrl+Alt+F<n>
to the guest OS and this will let you change consoles in your guest and also use other key combination that include Ctrl+Alt.