This window displays a virtual machine's graphical console. Paravirtual and full virtual machines use differenttechniques to export their local virtual framebuffers, but both technologies use VNC to make them available to the Virtual Machine Manager's console window. If your virtual machine is set to require authentication, the Virtual Machine Graphical console prompts you for a password before the display appears.
Your local desktop can intercept key combinations (for example, Ctrl+Alt+F11) to prevent them from being sent to the guest machine. You can use the Virtual Machine Manager's 'sticky key' capability to send these sequences. You must press any modifier key (like Ctrl or Alt) 3 times and that the key you specify will be treated as active until the next non-modifier key is pressed. Then you can send Ctrl-Alt-F11 to the guest by entering the key sequence 'Ctrl Ctrl Ctrl Alt+F1'.